ORCID Profile
0000-0002-3382-9558
Current Organisations
University of California Santa Cruz
,
University of Toronto
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy | Galactic Astronomy | Astronomical and Space Instrumentation | Astronomy And Astrophysics | Image Processing | Pure Mathematics | Macromolecular and Materials Chemistry | Chemical Sciences Not Elsewhere Classified | Topology | Earth Sciences Not Elsewhere Classified | Stellar Astronomy and Planetary Systems | Ionospheric And Magnetospheric Physics | Instruments And Techniques | Signal Processing | Lie Groups, Harmonic and Fourier Analysis | Information Storage, Retrieval And Management | Algebraic and Differential Geometry | Space and Solar Physics | High Energy Astrophysics; Cosmic Rays | Physical Sciences Not Elsewhere Classified
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Physical sciences | Scientific Instruments | Environmentally Sustainable Construction not elsewhere classified | Higher education | Chemical sciences | Scientific instrumentation | Education and Training not elsewhere classified | Computer software and services not elsewhere classified | Information Processing Services (incl. Data Entry and Capture) | Electronic Information Storage and Retrieval Services | Expanding Knowledge in the Mathematical Sciences |
Related Links
Publications
Advanced Diagnostics for the Study of Linearly Polarized Emission. I. Derivation
Publisher: American Astronomical Society
Date: 17-01-2018
Fourier Modeling of the Radio Torus Surrounding SN 1987A
Publisher: American Astronomical Society
Date: 09-2008
DOI: 10.1086/590330
The spectral energy distribution of powerful starburst galaxies – I. Modelling the radio continuum
Publisher: Oxford University Press (OUP)
Date: 09-10-2017
The Outer Scale of Turbulence in the Magnetoionized Galactic Interstellar Medium
Publisher: American Astronomical Society
Date: 10-06-2008
DOI: 10.1086/587165
Heightened Faraday complexity in the inner 1 kpc of the galactic centre
Publisher: Oxford University Press (OUP)
Date: 29-01-2021
Abstract: We have measured the Faraday rotation of 62 extra-galactic background sources in 58 fields using the CSIRO Australia Telescope Compact Array (ATCA) with a frequency range of 1.1–3.1 GHz with 2048 channels. Our sources cover a region $\sim 12\, \times 12\, \mathrm{deg^{ 2}}$ (∼1 kpc) around the Galactic Centre region. We show that the Galactic Plane for |l| & 10° exhibits large Rotation Measures (RMs) with a maximum |RM| of $1691.2 \pm 4.9\, \mathrm{rad}\, \mathrm{m}^{-2}$ and a mean $|\mathrm{RM}| = 219 \pm 42\, \mathrm{rad}\, \mathrm{m}^{-2}$. The RMs decrease in magnitude with increasing projected distance from the Galactic Plane, broadly consistent with previous findings. We find an unusually high fraction (95 per cent) of the sources show Faraday complexity consistent with multiple Faraday components. We attribute the presences of multiple Faraday rotating screens with widely separated Faraday depths to small-scale turbulent RM structure in the Galactic Centre region. The second-order structure function of the RM in the Galactic Centre displays a line with a gradient of zero for angular separations spanning 0.83°–11° (∼120–1500 pc), which is expected for scales larger than the outer scale (or driving scale) of magneto-ionic turbulence. We place an upper limit on any break in the SF gradient of 66 arcsec, corresponding to an inferred upper limit to the outer scale of turbulence in the inner 1 kpc of the Galactic Centre of 3 pc. We propose stellar feedback as the probable driver of this small-scale turbulence.
A Sudden Period of High Activity from Repeating Fast Radio Burst 20201124A
Publisher: American Astronomical Society
Date: 03-2022
Abstract: The repeating FRB 20201124A was first discovered by CHIME/FRB in November of 2020, after which it was seen to repeat a few times over several months. It entered a period of high activity in April of 2021, at which time several observatories recorded tens to hundreds more bursts from the source. These follow-up observations enabled precise localization and host-galaxy identification. In this paper, we report on the CHIME/FRB-detected bursts from FRB 20201124A, including their best-fit morphologies, fluences, and arrival times. The large exposure time of the CHIME/FRB telescope toward the location of this source allows us to constrain its rates of activity. We analyze the repetition rates over different spans of time, constraining the rate prior to discovery to .4 day −1 (at 3 σ ), and demonstrate a significant change in the event rate following initial detection. Lastly, we perform a maximum-likelihood estimation of a power-law luminosity function, finding a best-fit index α = −4.6 ± 1.3 ± 0.6, with a break at a fluence threshold of F min ∼ 16.6 Jy ms, consistent with the fluence completeness limit of the observations. This index is consistent within uncertainties with those of other repeating FRBs for which it has been determined.
Blobcat: Software to catalogue flood-filled blobs in radio images of total intensity and linear polarization
Publisher: Oxford University Press (OUP)
Date: 14-08-2012
Measurement of Spectral Breaks in Pulsar Wind Nebulae with Millimeter-Wave Interferometry
Publisher: American Astronomical Society
Date: 10-06-2005
DOI: 10.1086/429789
Spectropolarimetry of supernova remnant G296.5 + 10.0
Publisher: Cambridge University Press (CUP)
Date: 11-2009
DOI: 10.1017/S1743921309030373
Abstract: Radio continuum emission from the supernova remnant G296.5 + 10.0 was observed using the Australia Telescope Compact Array. Using a 104 MHz bandwidth split into 13 × 8 MHz spectral channels, it was possible to produce a pixel-by-pixel image of Rotation Measure (RM) across the entire remnant. A lack of correlation between RM and X-ray surface brightness reveals that the RMs originate from outside the remnant. Using this information, we will characterise the smooth component of the magnetic field within the supernova remnant and attempt to probe the magneto-ionic structure and turbulent scale sizes in the ISM and galactic halo along the line-of-sight.
Imaging of the Radio Remnant of SN 1987A at 12 mm Wavelength
Publisher: American Astronomical Society
Date: 12-07-2005
DOI: 10.1086/432836
The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis
Publisher: American Astronomical Society
Date: 12-2006
DOI: 10.1086/508467
A Tale of Two Current Sheets
Publisher: Springer Berlin Heidelberg
Date: 14-12-2010
Magnetic fields in the Southern Galactic Plane Survey
Publisher: Wiley
Date: 16-05-2006
Abstract: The Southern Galactic Plane Survey (SGPS) is a 1.4 GHz radio polarization and H I survey in a large part of the inner Galactic plane at a resolution of about an arcmin. Depolarization and Faraday rotation of polarized radiation from diffuse Galactic synchrotron emission, pulsars, and extragalactic sources can be used to infer information about the strength and structure of the Galactic magnetic field. Here, we discuss early results of the polarization data from the SGPS. We show from statistical analysis of rotation measures of polarized extragalactic sources that fluctuations in the magnetoionized medium of the spiral arms are probably mainly caused by H II regions, while the rotation measure fluctuations in the interarm regions may be connected to the interstellar turbulent cascade. Furthermore, the variations of rotation measure with Galactic longitude enable modeling of the large‐scale component of the Galactic magnetic field, including determination of the number and location of magnetic field reversals. Finally, the SGPS is an excellent way to study subparsec‐scale structure in the ionized interstellar medium by way of depolarization studies in H II regions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754
Publisher: American Astronomical Society
Date: 10-05-2002
DOI: 10.1086/340973
Observations of fast radio bursts at frequencies down to 400 megahertz
Publisher: Springer Science and Business Media LLC
Date: 09-01-2019
DOI: 10.1038/S41586-018-0867-7
Abstract: Fast radio bursts (FRBs) are highly dispersed millisecond-duration radio flashes probably arriving from far outside the Milky Way
PSR J1016-5857: A Young Radio Pulsar with Possible Supernova Remnant, X-Ray, and Gamma-Ray Associations
Publisher: American Astronomical Society
Date: 10-08-2001
DOI: 10.1086/323171
The First CHIME/FRB Fast Radio Burst Catalog
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present a catalog of 536 fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project between 400 and 800 MHz from 2018 July 25 to 2019 July 1, including 62 bursts from 18 previously reported repeating sources. The catalog represents the first large s le, including bursts from repeaters and nonrepeaters, observed in a single survey with uniform selection effects. This facilitates comparative and absolute studies of the FRB population. We show that repeaters and apparent nonrepeaters have sky locations and dispersion measures (DMs) that are consistent with being drawn from the same distribution. However, bursts from repeating sources differ from apparent nonrepeaters in intrinsic temporal width and spectral bandwidth. Through injection of simulated events into our detection pipeline, we perform an absolute calibration of selection effects to account for systematic biases. We find evidence for a population of FRBs—composing a large fraction of the overall population—with a scattering time at 600 MHz in excess of 10 ms, of which only a small fraction are observed by CHIME/FRB. We infer a power-law index for the cumulative fluence distribution of α = − 1.40 ± 0.11 ( stat. ) − 0.09 + 0.06 ( sys. ) , consistent with the −3/2 expectation for a nonevolving population in Euclidean space. We find that α is steeper for high-DM events and shallower for low-DM events, which is what would be expected when DM is correlated with distance. We infer a sky rate of [ 820 ± 60 ( stat. ) − 200 + 220 ( sys. ) ] / sky / day above a fluence of 5 Jy ms at 600 MHz, with a scattering time at 600 MHz under 10 ms and DM above 100 pc cm −3 .
High-energy sources at low radio frequency: the Murchison Widefield Array view ofFermiblazars
Publisher: EDP Sciences
Date: 04-2016
The Global Magneto-Ionic Medium Survey (GMIMS): the brightest polarized region in the southern sky at 75 cm and its implications for Radio Loop II
Publisher: Oxford University Press (OUP)
Date: 28-06-2021
Abstract: Using the Global Magneto-Ionic Medium Survey (GMIMS) Low-Band South (LBS) southern sky polarization survey, covering 300–480 MHz at 81 arcmin resolution, we reveal the brightest region in the southern polarized sky at these frequencies. The region, G150−50, covers nearly 20 $\\deg ^2$, near (l, b) ≈ (150○, −50○). Using GMIMS-LBS and complementary data at higher frequencies (∼0.6–30 GHz), we apply Faraday tomography and Stokes QU-fitting techniques. We find that the magnetic field associated with G150−50 is both coherent and primarily in the plane of the sky, and indicates that the region is associated with Radio Loop II. The Faraday depth spectra across G150−50 are broad and contain a large-scale spatial gradient. We model the magnetic field in the region as an expanding shell, and we can reproduce both the observed Faraday rotation and the synchrotron emission in the GMIMS-LBS band. Using QU fitting, we find that the Faraday spectra are produced by several Faraday dispersive sources along the line of sight. Alternatively, polarization horizon effects that we cannot model are adding complexity to the high-frequency polarized spectra. The magnetic field structure of Loop II dominates a large fraction of the sky, and studies of the large-scale polarized sky will need to account for this object. Studies of G150−50 with high angular resolution could mitigate polarization horizon effects, and clarify the nature of G150−50.
Discovery of X‐Ray Pulsations from the Compact Central Source in the Supernova Remnant 3C 58
Publisher: American Astronomical Society
Date: 20-03-2002
DOI: 10.1086/338766
A STUDY of BROADBAND FARADAY ROTATION and POLARIZATION BEHAVIOR over 1.3-10 GHz in 36 DISCRETE RADIO SOURCES
Publisher: American Astronomical Society
Date: 29-06-2016
AN EXTREME PULSAR TAIL PROTRUDING FROM THE FRYING PAN SUPERNOVA REMNANT
Publisher: American Astronomical Society
Date: 27-01-2012
The Radio Emission, X-Ray Emission, and Hydrodynamics of G328.4+0.2: A Comprehensive Analysis of a Luminous Pulsar Wind Nebula, Its Neutron Star, and the Progenitor Supernova Explosion
Publisher: American Astronomical Society
Date: 07-2007
DOI: 10.1086/518498
Rotation Measures of Extragalactic Sources behind the Southern Galactic Plane: New Insights into the Large-Scale Magnetic Field of the Inner Milky Way
Publisher: American Astronomical Society
Date: 07-2007
DOI: 10.1086/518499
Cosmic magnetism with the Square Kilometre Array and its pathfinders
Publisher: Cambridge University Press (CUP)
Date: 11-2009
DOI: 10.1017/S1743921309031470
Abstract: One of the five key science projects for the Square Kilometre Array (SKA) is “The Origin and Evolution of Cosmic Magnetism”, in which radio polarimetry will be used to reveal what cosmic magnets look like and what role they have played in the evolving Universe. Many of the SKA prototypes now being built are also targeting magnetic fields and polarimetry as key science areas. Here I review the prospects for innovative new polarimetry and Faraday rotation experiments with forthcoming facilities such as ASKAP, LOFAR, the ATA, the EVLA, and ultimately the SKA. Sensitive wide-field polarisation surveys with these telescopes will provide a dramatic new view of magnetic fields in the Milky Way, in nearby galaxies and clusters, and in the high-redshift Universe.
Measurement of a Magnetic Field in a Leading Arm High-velocity Cloud
Publisher: American Astronomical Society
Date: 17-11-2010
MODELING THE MAGNETIC FIELD IN THE GALACTIC DISK USING NEW ROTATION MEASURE OBSERVATIONS FROM THE VERY LARGE ARRAY
Publisher: American Astronomical Society
Date: 25-01-2011
ChandraandXMM‐NewtonObservations of the Vela‐like Pulsar B1046−58
Publisher: American Astronomical Society
Date: 20-11-2006
DOI: 10.1086/507125
The Discovery of an Eccentric Millisecond Pulsar in the Galactic Plane
Publisher: AIP
Date: 2008
DOI: 10.1063/1.2900272
The extended X–ray emission around RRAT J1819–1458
Publisher: Cambridge University Press (CUP)
Date: 08-2012
DOI: 10.1017/S1743921312023800
Abstract: We present new imaging and spectral analysis of the recently discovered extended X–ray emission around the high-magnetic-field rotating radio transient RRAT J1819–1458. We used two Chandra observations, taken on 2008 May 31 and 2011 May 28. The diffuse X–ray emission was detected with a significance of ~19σ in the image obtained by combining the two observations. Long-term spectral variability has not been observed. Possible scenarios for the origin of this diffuse X–ray emission, further detailed in Camero–Arranz et al . (2012), are here discussed.
Revealing the Faraday depth structure of radio galaxy NGC612 with broad-band radio polarimetric observations
Publisher: Oxford University Press (OUP)
Date: 05-02-2018
DOI: 10.1093/MNRAS/STY269
Giant magnetized outflows from the centre of the Milky Way
Publisher: Springer Science and Business Media LLC
Date: 2013
DOI: 10.1038/NATURE11734
Abstract: The nucleus of the Milky Way is known to harbour regions of intense star formation activity as well as a supermassive black hole. Recent observations have revealed regions of γ-ray emission reaching far above and below the Galactic Centre (relative to the Galactic plane), the so-called 'Fermi bubbles'. It is uncertain whether these were generated by nuclear star formation or by quasar-like outbursts of the central black hole and no information on the structures' magnetic field has been reported. Here we report observations of two giant, linearly polarized radio lobes, containing three ridge-like substructures, emanating from the Galactic Centre. The lobes each extend about 60 degrees in the Galactic bulge, closely corresponding to the Fermi bubbles, and are permeated by strong magnetic fields of up to 15 microgauss. We conclude that the radio lobes originate in a biconical, star-formation-driven (rather than black-hole-driven) outflow from the Galaxy's central 200 parsecs that transports a huge amount of magnetic energy, about 10(55) ergs, into the Galactic halo. The ridges wind around this outflow and, we suggest, constitute a 'phonographic' record of nuclear star formation activity over at least ten million years.
Simulated faraday rotation measures toward high galactic latitudes
Publisher: American Astronomical Society
Date: 05-04-2013
A Serendipitous MWA Search for Narrowband Signals from 'Oumuamua
Publisher: American Astronomical Society
Date: 09-04-2018
FIRST SEASON MWA EOR POWER SPECTRUM RESULTS AT REDSHIFT 7
Publisher: American Astronomical Society
Date: 09-12-2016
A search for the radio counterpart of the unidentified γ-ray source 3EG J1410-6147
Publisher: Oxford University Press (OUP)
Date: 03-2003
Pulsar wind nebulae in EGRET error boxes
Publisher: Springer Science and Business Media LLC
Date: 06-2005
Polarization Gradient Study of Interstellar Medium Turbulence Using the Canadian Galactic Plane Survey
Publisher: American Astronomical Society
Date: 31-01-2017
Periodic activity from a fast radio burst source
Publisher: Springer Science and Business Media LLC
Date: 17-06-2020
The Fan Region at 1.5 GHz. I: Polarized synchrotron emission extending beyond the Perseus Arm
Publisher: Oxford University Press (OUP)
Date: 16-02-2017
DOI: 10.1093/MNRAS/STX389
A Long Overdue Synthesis Image of Centaurus A
Publisher: Springer Netherlands
Date: 2008
A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array
Publisher: Oxford University Press (OUP)
Date: 19-01-2017
DOI: 10.1093/MNRAS/STX155
Tracking the Outer Spiral Arms of the Galaxy in H I Absorption
Publisher: American Astronomical Society
Date: 23-10-2007
DOI: 10.1086/522794
Observations of X-Rays and Thermal Dust Emission from the Supernova Remnant Kes 75
Publisher: American Astronomical Society
Date: 20-09-2007
DOI: 10.1086/520496
Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array
Publisher: Oxford University Press (OUP)
Date: 02-09-2015
The Infrared Detection of the Pulsar Wind Nebula in the Galactic Supernova Remnant 3C 58
Publisher: American Astronomical Society
Date: 03-03-2008
DOI: 10.1086/587031
LOW-FREQUENCY OBSERVATIONS OF LINEARLY POLARIZED STRUCTURES IN THE INTERSTELLAR MEDIUM NEAR THE SOUTH GALACTIC POLE
Publisher: American Astronomical Society
Date: 10-10-2016
Radio observations of PSR B1259 -- 63 around periastron
Publisher: Oxford University Press (OUP)
Date: 04-1996
Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds from ASAS-SN: Implications for Thorne–Żytkow Objects and Super-asymptotic Giant Branch Stars
Publisher: American Astronomical Society
Date: 30-09-2020
The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14 110 Compact Radio Sources over 6 100 Square Degrees
Publisher: Cambridge University Press (CUP)
Date: 2014
DOI: 10.1017/PASA.2014.40
Abstract: We present the results of an approximately 6 100 deg 2 104–196 MHz radio sky survey performed with the Murchison Widefield Array during instrument commissioning between 2012 September and 2012 December: the MWACS. The data were taken as meridian drift scans with two different 32-antenna sub-arrays that were available during the commissioning period. The survey covers approximately 20.5 h RA 8.5 h, − 58° Dec −14°over three frequency bands centred on 119, 150 and 180 MHz, with image resolutions of 6–3 arcmin. The catalogue has 3 arcmin angular resolution and a typical noise level of 40 mJy beam − 1 , with reduced sensitivity near the field boundaries and bright sources. We describe the data reduction strategy, based upon mosaicked snapshots, flux density calibration, and source-finding method. We present a catalogue of flux density and spectral index measurements for 14 110 sources, extracted from the mosaic, 1 247 of which are sub-components of complexes of sources.
A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud
Publisher: American Astronomical Society
Date: 12-2008
DOI: 10.1086/590546
Extragalactic Peaked-spectrum Radio Sources at Low Frequencies
Publisher: American Astronomical Society
Date: 17-02-2017
A large age for the pulsar B1757-24 from an upper limit on its proper motion
Publisher: Springer Science and Business Media LLC
Date: 07-2000
DOI: 10.1038/35018010
Abstract: The 'characteristic age' of a pulsar is usually considered to approximate its true age, but this assumption has led to some puzzling results, including the fact that many pulsars with small characteristic ages have no associated supernova remnants. The pulsar B1757-24 is located just outside the edge of a supernova remnant the properties of the system indicate that the pulsar was born at the centre of the remnant with a substantial velocity, and that it has subsequently overtaken the expanding blast wave. With a characteristic age of 16,000 yr, the pulsar is expected to have a proper motion of 63-80 milliarcseconds (mas) per year. Here we report observations of the nebula surrounding the pulsar, which limit its proper motion to less than 25 mas yr(-1), implying a minimum age of 39,000 yr. A more detailed analysis argues that the true age may be as great as 170,000 yr, which is significantly larger than the characteristic age. We conclude from this result and other discrepancies associated with pulsars that characteristic ages greatly underestimate the true ages of pulsars.
Magnetism Science with the Square Kilometre Array
Publisher: MDPI AG
Date: 06-07-2020
Abstract: The Square Kilometre Array (SKA) will answer fundamental questions about the origin, evolution, properties, and influence of magnetic fields throughout the Universe. Magnetic fields can illuminate and influence phenomena as erse as star formation, galactic dynamics, fast radio bursts, active galactic nuclei, large-scale structure, and dark matter annihilation. Preparations for the SKA are swiftly continuing worldwide, and the community is making tremendous observational progress in the field of cosmic magnetism using data from a powerful international suite of SKA pathfinder and precursor telescopes. In this contribution, we revisit community plans for magnetism research using the SKA, in light of these recent rapid developments. We focus in particular on the impact that new radio telescope instrumentation is generating, thus advancing our understanding of key SKA magnetism science areas, as well as the new techniques that are required for processing and interpreting the data. We discuss these recent developments in the context of the ultimate scientific goals for the SKA era.
Discovery of a Filamentary Synchrotron Structure Connected to the Coherent Magnetic Field in the Outer Galaxy
Publisher: American Astronomical Society
Date: 12-2022
Abstract: Using data from the Galactic Arecibo L -band Feed Array Continuum Transit Survey, we report the discovery of two previously unidentified, very compressed, thin, and straight polarized filaments approximately centered at Galactic coordinates, ( l , b ) = (182.°5, − 4.°0), which we call G182.5–4.0. Using data from the Isaac Newton Telescope Galactic Plane Survey, we also find straight, long, and extremely thin H α filaments coincident with the radio emission. These filaments are positioned in projection at the edge of the Orion-Eridanus superbubble and we find evidence indicating that the filaments align with the coherent magnetic field of the outer Galaxy. We find a lower limit on the total radio flux at 1.4 GHz to be 0.7 ± 0.3 Jy with an average linearly polarized fraction of 40 − 20 + 30 % . We consider various scenarios that could explain the origin of these filaments, including a shell-type supernova remnant (SNR), a bow shock nebula associated with a pulsar, or relic fragments from one or more supernova explosions in the adjacent superbubble, with a hybrid scenario being most likely. This may represent an ex le of a new class of objects that is neither an SNR nor a bow shock. The highly compressed nature of these filaments and their alignment with the Galactic plane suggests a scenario where this object formed in a magnetic field that was compressed by the expanding Orion-Eridanus superbubble, suggesting that the object is related to this superbubble and implying a distance of ∼400 pc.
FAST RADIO BURSTS AS PROBES OF MAGNETIC FIELDS IN THE INTERGALACTIC MEDIUM
Publisher: American Astronomical Society
Date: 20-06-2016
The Global Magneto-Ionic Medium Survey: Polarimetry of the Southern Sky from 300 to 480 MHz
Publisher: American Astronomical Society
Date: 02-07-2019
Fitting together the H I absorption and emission in the Southern Galactic Plane Survey
Publisher: American Astronomical Society
Date: 10-03-2003
DOI: 10.1086/346081
DISCOVERY OF THE ENERGETIC PULSAR J1747–2809 IN THE SUPERNOVA REMNANT G0.9+0.1
Publisher: American Astronomical Society
Date: 30-06-2009
Discovery of 35 New Supernova Remnants in the Inner Galaxy
Publisher: American Astronomical Society
Date: 09-02-2006
DOI: 10.1086/501500
A new search for distant radio galaxies in the Southern hemisphere - III. Optical spectroscopy and analysis of the MRCR-SUMSS sample
Publisher: Oxford University Press (OUP)
Date: 11-05-2009
A PROPER MOTION FOR THE PULSAR WIND NEBULA G359.23–0.82, THE “MOUSE,” ASSOCIATED WITH THE ENERGETIC RADIO PULSAR J1747–2958
Publisher: American Astronomical Society
Date: 11-11-2009
CHASING THE IDENTIFICATION OF ASCA GALACTIC OBJECTS (ChIcAGO): AN X-RAY SURVEY OF UNIDENTIFIED SOURCES IN THE GALACTIC PLANE. I. SOURCE SAMPLE AND INITIA
Publisher: American Astronomical Society
Date: 28-04-2014
A BROADBAND POLARIZATION CATALOG OF EXTRAGALACTIC RADIO SOURCES
Publisher: American Astronomical Society
Date: 02-05-2014
A RADIO-POLARIZATION AND ROTATION MEASURE STUDY OF THE GUM NEBULA AND ITS ENVIRONMENT
Publisher: American Astronomical Society
Date: 24-04-2015
Limits on Fast Radio Burst–like Counterparts to Gamma-Ray Bursts Using CHIME/FRB
Publisher: American Astronomical Society
Date: 09-2023
Anomalous X-ray pulsars and soft gamma-ray repeaters - the connection with supernova remnants
Publisher: Elsevier BV
Date: 2004
La découverte à la frontière cosmique: Plan à long terme de l'astronomie canadienne 2020-2030
Publisher: Zenodo
Date: 2021
Lost and Found: A New Position and Infrared Counterpart for the X-Ray Binary Scutum X-1
Publisher: American Astronomical Society
Date: 20-05-2007
DOI: 10.1086/513712
The Square Kilometre Array: a new probe of cosmic magnetism
Publisher: Wiley
Date: 16-05-2006
Abstract: Magnetic fields are a fundamental part of many astrophysical phenomena, but the evolution, structure and origin of magnetic fields are still unresolved problems in physics and astrophysics. When and how were the first fields generated? Are present‐day magnetic fields the result of standard dynamo action, or do they represent rapid or recent field lification through other processes? What role do magnetic fields play in turbulence, cosmic ray acceleration and structure formation? I explain how the Square Kilometre Array (SKA), a next‐generation radio telescope, can deliver stunning new data‐sets that will address these currently unanswered issues. The foundation for these experiments will be an all‐sky survey of rotation measures, in which Faraday rotation toward 10 7 background sources will provide a dense grid for probing magnetism in the Milky Way, nearby galaxies, and in distant galaxies, clusters and protogalaxies. Using these data, we can map out the evolution of magnetized structures from redshifts z 3 to the present, can distinguish between different origins for seed magnetic fields in galaxies, and can develop a detailed model of the magnetic field geometry of the intergalactic medium and of the overall Universe. In addition, the SKA will certainly discover new magnetic phenomena beyond what we can currently predict or imagine. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Vertical Structure of Warm Ionised Gas in the Milky Way
Publisher: Cambridge University Press (CUP)
Date: 2008
DOI: 10.1071/AS08004
Abstract: We present a new joint analysis of pulsar dispersion measures and diffuse H α emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by H ii regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830 –250 +120 pc, a factor of two larger than has been derived in previous studies. The corresponding inconsistent scale heights for dispersion measure and emission measure imply that the vertical profiles of mass and pressure in the WIM are decoupled, and that the filling factor of WIM clouds is a geometric response to the competing environmental influences of thermal and non-thermal processes. Extrapolating the properties of the thick-disk WIM to mid-plane, we infer a volume-averaged electron density 0.014 ± 0.001 cm −3 , produced by clouds of typical electron density 0.34 ± 0.06 cm −3 with a volume filling factor 0.04 ± 0.01. As one moves off the plane, the filling factor increases to a maximum of ∼30% at a height of ≈1–1.5 kpc, before then declining to accommodate the increasing presence of hot, coronal gas. Since models for the WIM with a ≈1 kpc scale-height have been widely used to estimate distances to radio pulsars, our revised parameters suggest that the distances to many high-latitude pulsars have been substantially underestimated.
Through thick or thin: multiple components of the magneto-ionic medium towards the nearby H ii region Sharpless 2–27 revealed by Faraday tomography
Publisher: Oxford University Press (OUP)
Date: 24-05-2019
The 30 Year Search for the Compact Object in SN 1987A
Publisher: American Astronomical Society
Date: 13-09-2018
Estimating extragalactic Faraday rotation
Publisher: EDP Sciences
Date: 03-2015
Optical Identification of Multiple Faint X-Ray Sources in the Globular Cluster NGC 6752: Evidence for Numerous Cataclysmic Variables
Publisher: American Astronomical Society
Date: 04-2002
DOI: 10.1086/339210
PSR J1833−1034: Discovery of the Central Young Pulsar in the Supernova Remnant G21.5–0.9
Publisher: American Astronomical Society
Date: 20-01-2006
DOI: 10.1086/498386
Ghost of a shell: magnetic fields of Galactic supershell GSH 006 - 15 + 7
Publisher: Oxford University Press (OUP)
Date: 19-07-2018
GMIMS: the Global Magneto-Ionic Medium Survey
Publisher: Cambridge University Press (CUP)
Date: 11-2009
DOI: 10.1017/S1743921309030117
Abstract: The Global Magneto-Ionic Medium Survey (GMIMS) is a project to map the diffuse polarized emission over the entire sky, Northern and Southern hemispheres, from 300 MHz to 1.8 GHz. With an angular resolution of 30–60 arcmin and a frequency resolution of 1 MHz or better, GMIMS will provide the first spectro-polarimetric data set of the large-scale polarized emission over the entire sky, observed with single-dish telescopes. GMIMS will provide an invaluable resource for studies of the magneto-ionic medium of the Galaxy in the local disk, halo, and its transition.
The radio continuum structure of centaurus a at 1.4GHz
Publisher: American Astronomical Society
Date: 20-09-2011
A Precise Proper Motion for the Crab Pulsar, and the Difficulty of Testing Spin‐Kick Alignment for Young Neutron Stars
Publisher: American Astronomical Society
Date: 20-04-2008
DOI: 10.1086/529026
Discovery of an optical bow-shock around pulsar B0740-28
Publisher: EDP Sciences
Date: 14-06-2002
High-resolution Observations of Low-luminosity Gigahertz-Peaked Spectrum and Compact Steep Spectrum Sources
Publisher: Oxford University Press (OUP)
Date: 03-03-2018
DOI: 10.1093/MNRAS/STY564
SMSS J130522.47−293113.0: a high-latitude stellar X-ray source with pc-scale outflow relics?
Publisher: Oxford University Press (OUP)
Date: 16-03-2018
DOI: 10.1093/MNRAS/STY680
A Local Universe Host for the Repeating Fast Radio Burst FRB 20181030A
Publisher: American Astronomical Society
Date: 30-09-2021
The (Re-)Discovery of G350.1-0.3: A Young, Luminous Supernova Remnant and Its Neutron Star
Publisher: American Astronomical Society
Date: 13-05-2008
DOI: 10.1086/589650
PSR J1124-5916: Discovery of a young energetic pulsar in the supernova remnant G292.0+1.8
Publisher: American Astronomical Society
Date: 08-02-2002
DOI: 10.1086/339799
A Matched Filter Technique for Slow Radio Transient Detection and First Demonstration with the Murchison Widefield Array
Publisher: American Astronomical Society
Date: 07-02-2017
Helicity in the large-scale Galactic magnetic field
Publisher: Oxford University Press (OUP)
Date: 08-10-2020
Abstract: We search for observational signatures of magnetic helicity in data from all-sky radio polarization surveys of the Milky Way Galaxy. Such a detection would help confirm the dynamo origin of the field and may provide new observational constraints for its shape. We compare our observational results to simulated observations for both a simple helical field, and for a more complex field that comes from a solution to the dynamo equation. Our simulated observations show that the large-scale helicity of a magnetic field is reflected in the large-scale structure of the fractional polarization derived from the observed synchrotron radiation and Faraday depth of the diffuse Galactic synchrotron emission. Comparing the models with the observations provides evidence for the presence of a quadrupolar magnetic field with a vertical component that is pointing away from the observer in both hemispheres of the Milky Way Galaxy. Since there is no reason to believe that the Galactic magnetic field is unusual when compared to other galaxies, this result provides further support for the dynamo origin of large-scale magnetic fields in galaxies.
Observations of magnetic fields in the Milky Way and in nearby galaxies with a Square Kilometre Array
Publisher: Elsevier BV
Date: 12-2004
Chandra Observations of the Transient 7 s X-ray Pulsar AX J1845.0-0258
Publisher: American Astronomical Society
Date: 20-11-2006
DOI: 10.1086/507262
X-Ray Timing of the Young Pulsar in 3C 58
Publisher: AIP
Date: 2004
DOI: 10.1063/1.1781054
Broad-band radio circular polarization spectrum of the relativistic jet in PKS B2126-158
Publisher: Oxford University Press (OUP)
Date: 07-08-2013
An x-ray nebula associated with the millisecond pulsar B1957+20
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-02-2003
Abstract: We have detected an x-ray nebula around the binary millisecond pulsar B1957+20. A narrow tail, corresponding to the shocked pulsar wind, is seen interior to the known Hα bow shock and proves the long-held assumption that the rotational energy of millisecond pulsars is dissipated through relativistic winds. Unresolved x-ray emission likely represents the shock where the winds of the pulsar and its companion collide. This emission indicates that the efficiency with which relativistic particles are accelerated in the postshock flow is similar to that for young pulsars, despite the shock proximity and much weaker surface magnetic field of this millisecond pulsar.
SNR G320.4-01.2 and PSR B1509-58: New radio observations of a complex interacting system
Publisher: Oxford University Press (OUP)
Date: 21-05-1999
Identification of a population of X-ray-emitting massive stars in the Galactic plane
Publisher: American Astronomical Society
Date: 11-01-2011
The pulsar/supernova remnant connection
Publisher: Oxford University Press (OUP)
Date: 15-12-1995
Two large H I shells in the outer galaxy near l = 279°
Publisher: American Astronomical Society
Date: 06-2000
DOI: 10.1086/301413
A Unified Model for the Fan Region and the North Polar Spur: A Bundle of Filaments in the Local Galaxy
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present a simple, unified model that can explain two of the brightest, large-scale, diffuse, polarized radio features in the sky, the North Polar Spur (NPS) and the Fan Region, along with several other prominent loops. We suggest that they are long, magnetized, and parallel filamentary structures that surround the Local arm and/or Local Bubble, in which the Sun is embedded. We show that this model is consistent with the large number of observational studies on these regions and is able to resolve an apparent contradiction in the literature that suggests that the high-latitude portion of the NPS is nearby, while lower-latitude portions are more distant. Understanding the contributions of this local emission is critical to developing a complete model of the Galactic magnetic field. These very nearby structures also provide context to help understand similar nonthermal, filamentary structures that are increasingly being observed with modern radio telescopes.
Pulsar Bow Shocks as Probes of Warm Neutral Gas
Publisher: Kluwer Academic Publishers
Date: 2004
Visibility stacking in the quest for type Ia supernova radio emission
Publisher: American Astronomical Society
Date: 21-06-2011
Addendum: “X-Ray Sources and Their Optical Counterparts in the Globular Cluster M4” (ApJ, 609, 755 [2004])
Publisher: American Astronomical Society
Date: 02-2005
DOI: 10.1086/426683
The origin and evolution of cosmic magnetism
Publisher: Elsevier BV
Date: 12-2004
Upper Limits on Periodic, Pulsed Radio Emission from the X-Ray Point Source in Cassiopeia A
Publisher: American Astronomical Society
Date: 20-01-2001
DOI: 10.1086/318891
ChandraImaging of the X‐Ray Nebula Powered by Pulsar B1509−58
Publisher: American Astronomical Society
Date: 20-04-2002
DOI: 10.1086/339354
BROADBAND RADIO POLARIMETRY and FARADAY ROTATION of 563 EXTRAGALACTIC RADIO SOURCES
Publisher: American Astronomical Society
Date: 08-12-2015
DOI: 10.1088/0004-637X/815/1/49
Abstract: We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the presence of material possessing complicated magnetoionic structure along the line of sight (LOS). For sources classified as Faraday-complex, we have analyzed a number of their radio and multiwavelength properties to determine whether they differ from Faraday-simple polarized sources (sources for which LOS magnetoionic structures are comparatively simple) in these properties. We use this information to constrain the physical nature of the magnetoionic structures responsible for generating the observed complexity. We detect Faraday complexity in 12% of polarized sources at ∼1′ resolution, but we demonstrate that underlying signal-to-noise limitations mean the true percentage is likely to be significantly higher in the polarized radio source population. We find that the properties of Faraday-complex objects are erse, but that complexity is most often associated with depolarization of extended radio sources possessing a relatively steep total intensity spectrum. We find an association between Faraday complexity and LOS structure in the Galactic interstellar medium (ISM) and claim that a significant proportion of the Faraday complexity we observe may be generated at interfaces of the ISM associated with ionization fronts near neutral hydrogen structures. Galaxy cluster environments and internally generated Faraday complexity provide possible alternative explanations in some cases.
A multiwavelength study of the radio source G296.7-0.9: Confirmation as a Galactic supernova remnant
Publisher: Oxford University Press (OUP)
Date: 18-11-2012
Nine New Repeating Fast Radio Burst Sources from CHIME/FRB
Publisher: American Astronomical Society
Date: 26-02-2020
RADIO POLARIZATION OBSERVATIONS OF THE SNAIL: A CRUSHED PULSAR WIND NEBULA IN G327.1–1.1 WITH A HIGHLY ORDERED MAGNETIC FIELD
Publisher: American Astronomical Society
Date: 24-03-2016
A Large-scale Magneto-ionic Fluctuation in the Local Environment of Periodic Fast Radio Burst Source FRB 20180916B
Publisher: American Astronomical Society
Date: 06-2023
Abstract: Fast radio burst (FRB) source FRB 20180916B exhibits a 16.33-day periodicity in its burst activity. It is as of yet unclear what proposed mechanism produces the activity, but polarization information is a key diagnostic. Here we report on the polarization properties of 44 bursts from FRB 20180916B detected between 2018 December and 2021 December by CHIME/FRB, the FRB project on the Canadian Hydrogen Intensity Mapping Experiment. In contrast to previous observations, we find significant variations in the Faraday rotation measure (RM) of FRB 20180916B. Over the 9-month period 2021 April and 2021 December we observe an apparent secular increase in RM of ∼50 rad m −2 (a fractional change of over 40%) that is accompanied by a possible drift of the emitting band to lower frequencies. This interval displays very little variation in the dispersion measure (ΔDM ≲ 0.8 pc cm −3 ), which indicates that the observed RM evolution is likely produced from coherent changes in the Faraday-active medium’s magnetic field. Burst-to-burst RM variations appear unrelated to the activity cycle phase. The degree of linear polarization of our burst s le (≳80%) is consistent with the negligible depolarization expected for this source in the 400–800 MHz bandpass of CHIME. FRB 20180916B joins other repeating FRBs in displaying substantial RM evolution. This is consistent with the notion that repeater progenitors may be associated with young stellar populations by their preferential occupation of dynamic magnetized environments commonly found in supernova remnants, in pulsar wind nebulae, or near high-mass stellar companions.
S–PASS view of polarized Galactic synchrotron at 2.3 GHz as a contaminant to CMB observations
Publisher: EDP Sciences
Date: 10-2018
DOI: 10.1051/0004-6361/201832768
Abstract: We have analyzed the southern sky emission in linear polarization at 2.3 GHz as observed by the S -band Polarization All Sky Survey ( S-PASS ). Our purpose is to study the properties of the diffuse Galactic polarized synchrotron as a contaminant to B -mode observations of the cosmic microwave background (CMB) polarization. We studied the angular distribution of the S-PASS signal at intermediate and high Galactic latitudes by means of the polarization angular power spectra. The power spectra, computed in the multipole interval 20 ≤ ℓ ≤ 1000, show a decay of the spectral litude as a function of multipole for ℓ ≲ 200, typical of the diffuse emission. At smaller angular scales, power spectra are dominated by the radio point source radiation. We find that, at low multipoles, spectra can be approximated by a power law C ℓ EE,BB ∝ ℓ α , with α ≃ −3, and characterized by a B -to- E ratio of about 0.5. We measured the polarized synchrotron spectral energy distribution (SED) in harmonic space, by combining S-PASS power spectra with low frequency WMAP and Planck ones, and by fitting their frequency dependence in six multipole bins, in the range 20 ≤ ℓ ≤ 140. Results show that the recovered SED, in the frequency range 2.3–33 GHz, is compatible with a power law with β s = −3.22 ± 0.08, which appears to be constant over the considered multipole range and in the different Galactic cuts. Combining the S-PASS total polarized intensity maps with those coming from WMAP and Planck we derived a map of the synchrotron spectral index β s at angular resolution of 2° on about 30% of the sky. The recovered β s distribution peaks at the value around −3.2. It exibits an angular power spectrum which can be approximated with a power law C ℓ ∝ ℓ γ with γ ≃ −2.6. We also measured a significant spatial correlation between synchrotron and thermal dust signals, as traced by the Planck 353 GHz channel. This correlation reaches about 40% on the larger angular scales, decaying considerably at the degree scales. Finally, we used the S-PASS maps to assess the polarized synchrotron contamination to CMB observations of the B -modes at higher frequencies. We ided the sky in small patches (with f sky ≃ 1%) and find that, at 90 GHz, the minimal contamination, in the cleanest regions of the sky, is at the level of an equivalent tensor-to-scalar ratio r synch ≃ 10 −3 . Moreover, by combining S-PASS data with Planck 353 GHz observations, we recover a map of the minimum level of total polarized foreground contamination to B -modes, finding that there is no region of the sky, at any frequency, where this contamination lies below equivalent tenor-to-scalar ratio r FG ≃ 10 −3 . This result confirms the importance of observing both high and low frequency foregrounds in CMB B -mode measurements.
Broad-band, radio spectro-polarimetric study of 100 radiative-mode and jet-mode AGN
Publisher: Oxford University Press (OUP)
Date: 15-05-2017
MAGNETIC FIELD STRUCTURE OF THE LARGE MAGELLANIC CLOUD FROM FARADAY ROTATION MEASURES OF DIFFUSE POLARIZED EMISSION
Publisher: American Astronomical Society
Date: 15-10-2012
Exciting the magnetosphere of the magnetar CXOU J164710.2-455216 in Westerlund 1
Publisher: Oxford University Press (OUP)
Date: 06-2007
The Outer Disk of the Milky Way Seen in λ21 cm Absorption
Publisher: American Astronomical Society
Date: 09-03-2009
OUT OF THE FRYING PAN: A YOUNG PULSAR WITH A LONG RADIO TRAIL EMERGING FROM SNR G315.9-0.0
Publisher: American Astronomical Society
Date: 02-09-2009
Chandra monitoring of the candidate anomalous X-ray pulsar AX J1845.0-0258
Publisher: Springer Science and Business Media LLC
Date: 20-03-2007
RMTable2023 and PolSpectra2023: Standards for Reporting Polarization and Faraday Rotation Measurements of Radio Sources
Publisher: American Astronomical Society
Date: 25-07-2023
Abstract: Faraday rotation measures (RMs) have been used for many studies of cosmic magnetism, and in most cases having more RMs is beneficial for those studies. This has lead to the development of RM surveys that have produced large catalogs, as well as meta-catalogs collecting RMs from many different publications. However, it has been difficult to take full advantage of all of these RMs, as the in idual catalogs have been published in many different places, and in many different formats. In addition, the polarization spectra used to determine these RMs are rarely published, limiting the ability to reanalyze data as new methods or additional observations become available. We propose a standard convention for RM catalogs, RMTable2023, and a standard for source-integrated polarized spectra of radio sources, PolSpectra2023. These standards are intended to maximize the value and utility of these data for researchers and to make them easier to access. To demonstrate the use of the RMTable2023 standard, we have produced a consolidated catalog of 55,819 RMs collected from 42 published catalogs.
Galactic interstellar turbulence across the southern sky seen through spatial gradients of the polarization vector
Publisher: EDP Sciences
Date: 29-05-2014
MAGNETIC FIELD DISORDER AND FARADAY EFFECTS ON THE POLARIZATION OF EXTRAGALACTIC RADIO SOURCES
Publisher: American Astronomical Society
Date: 13-09-2016
Erratum: A 22-yr southern sky survey for transient and variable radio sources using the Molonglo Observatory Synthesis Telescope
Publisher: Oxford University Press (OUP)
Date: 24-11-2011
Workshop on Radio Transients
Publisher: Cambridge University Press (CUP)
Date: 09-2012
DOI: 10.1017/S1743921312000749
Abstract: We are entering a new era in the study of variable and transient radio sources. This workshop discussed the instruments and the strategies employed to study those sources, how they are identified and classified, how results from different surveys can be compared, and how radio observations tie in with those at other wavelengths. The emphasis was on learning what common ground there is between the plethora of on-going projects, how methods and code can be shared, and how best practices regarding survey strategy could be adopted. The workshop featured the four topics below. Each topic commenced with a fairly brief introductory talk, which then developed into discussion. By way of preparation, participants had been invited to upload and discuss one slide per topic to a wiki ahead of the workshop. 1. Telescopes, instrumentation and survey strategy . New radio facilities and on-going projects (including upgrades) are both studying the variability of the radio sky, and searching for transients. The discussion first centred on the status of those facilities, and on projects with a time-domain focus, both ongoing and planned, before turning to factors driving choices of instrumentation, such as phased array versus single pixel feeds, the field of view, spatial and time resolution, frequency and bandwidth, depth, area, and cadence of the surveys. 2. Detection, pipelines, and classification . The workshop debated (a) the factors that influence decisions to study variability in the (u,v) plane, in images, or in catalogues, (b) whether, and how much, pipeline code could potentially be shared between one project and another, and which software packages are best for different approaches, (c) how data are stored and later accessed, and (d) how transients and variables are defined and classified. 3. Statistics, interpretation, and synthesis . It then discussed how (i) the choice of facility and strategy and (ii) detection and classification schemes influence what is seen (in terms of types of object and rates) by different surveys, (iii) how results from different surveys could be compared, and (iv) how what we know from existing surveys drives choices (i) and (ii), particularly as regards finding new classes of object. 4. Multiwavelength approaches . The workshop concluded by discussing what information is needed from wavelengths other than radio in order to classify transients and variables adequately and predict their rates as a function of topics (1), (2) and (3). It asked what the constraints are on responding to, and issuing triggers for, follow-up observations, and how that might feed back into considerations for designing our telescopes and surveys.
A second source of repeating fast radio bursts
Publisher: Springer Science and Business Media LLC
Date: 09-01-2019
DOI: 10.1038/S41586-018-0864-X
Abstract: The discovery of a repeating fast radio burst (FRB) source
THE MURCHISON WIDEFIELD ARRAY 21 cm POWER SPECTRUM ANALYSIS METHODOLOGY
Publisher: American Astronomical Society
Date: 11-07-2016
Magnetic Fields in the Milky Way Halo
Publisher: Cambridge University Press (CUP)
Date: 08-2015
DOI: 10.1017/S1743921314011727
Abstract: We present a study of the Milky Way halo magnetic field, determined from observations of Faraday rotation measure (RM) of extragalactic radio sources (EGS) in Galactic longitude range 100°–117° within 30° of the Galactic plane. We find negative median RMs in both the northern and southern Galactic hemispheres for | b | °, outside the latitude range where the disk field dominates. This suggest that the halo magnetic field towards the outer Galaxy does not reverse direction across the mid-plane. An azimuthal magnetic field at heights 0.8−2 kpc above/below the Galactic plane between the local and the Perseus spiral arm can reproduce the observed trend of RM against Galactic latitude. We propose that the Milky Way could have a halo magnetic field similar to that observed in M51.
ATLAS 1.4GHz data release 2 - II. Properties of the faint polarized sky
Publisher: Oxford University Press (OUP)
Date: 17-04-2014
DOI: 10.1093/MNRAS/STU500
The Growth, Polarization, and Motion of the Radio Afterglow from the Giant Flare from SGR 1806-20
Publisher: American Astronomical Society
Date: 08-11-2005
DOI: 10.1086/491648
A High-Resolution Foreground Model for the MWA EoR1 Field: Model and Implications for EoR Power Spectrum Analysis
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.26
Abstract: The current generation of experiments aiming to detect the neutral hydrogen signal from the Epoch of Reionisation (EoR) is likely to be limited by systematic effects associated with removing foreground sources from target fields. In this paper, we develop a model for the compact foreground sources in one of the target fields of the MWA’s EoR key science experiment: the ‘EoR1’ field. The model is based on both the MWA’s GLEAM survey and GMRT 150 MHz data from the TGSS survey, the latter providing higher angular resolution and better astrometric accuracy for compact sources than is available from the MWA alone. The model contains 5 049 sources, some of which have complicated morphology in MWA data, Fornax A being the most complex. The higher resolution data show that 13% of sources that appear point-like to the MWA have complicated morphology such as double and quad structure, with a typical separation of 33 arcsec. We derive an analytic expression for the error introduced into the EoR two-dimensional power spectrum due to peeling close double sources as single point sources and show that for the measured source properties, the error in the power spectrum is confined to high k ⊥ modes that do not affect the overall result for the large-scale cosmological signal of interest. The brightest 10 mis-modelled sources in the field contribute 90% of the power bias in the data, suggesting that it is most critical to improve the models of the brightest sources. With this hybrid model, we reprocess data from the EoR1 field and show a maximum of 8% improved calibration accuracy and a factor of two reduction in residual power in k -space from peeling these sources. Implications for future EoR experiments including the SKA are discussed in relation to the improvements obtained.
The evolution and structure of pulsar wind nebulae
Publisher: Annual Reviews
Date: 09-2006
DOI: 10.1146/ANNUREV.ASTRO.44.051905.092528
Abstract: Pulsars steadily dissipate their rotational energy via relativistic winds. Confinement of these outflows generates luminous pulsar wind nebulae, seen across the electromagnetic spectrum in synchrotron and inverse Compton emission and in optical emission lines when they shock the surrounding medium. These sources act as important probes of relativistic shocks, particle acceleration, and interstellar gas. We review the many recent advances in the study of pulsar wind nebulae, with particular focus on the evolutionary stages through which these objects progress as they expand into their surroundings, and on morphological structures within these nebulae that directly trace the physical processes of particle acceleration and outflow. We conclude by considering some exciting new probes of pulsar wind nebulae, including the study of TeV gamma-ray emission from these sources, and observations of pulsar winds in close binary systems.
Subarcminute Localization of 13 Repeating Fast Radio Bursts Detected by CHIME/FRB
Publisher: American Astronomical Society
Date: 06-2023
Abstract: We report on improved sky localizations of 13 repeating fast radio bursts (FRBs) discovered by CHIME/FRB via the use of interferometric techniques on channelized voltages from the telescope. These so-called “baseband localizations” improve the localization uncertainty area presented in past studies by more than three orders of magnitude. The improved localization regions are provided for the full s le of FRBs to enable follow-up studies. The localization uncertainties, together with the limits on the source distances from their dispersion measures, allow us to identify likely host galaxies for two of the FRB sources. FRB 20180814A lives in a massive passive red spiral at z ∼ 0.068 with very little indication of star formation, while FRB 20190303A resides in a merging pair of spiral galaxies at z ∼ 0.064 undergoing significant star formation. These galaxies show very different characteristics, further confirming the presence of FRB progenitors in a variety of environments even among the repeating subclass.
XMM-Newton Spectroscopy of the Galactic Microquasar GRS 1758-258 in the Peculiar Off/Soft State
Publisher: American Astronomical Society
Date: 10-02-2002
DOI: 10.1086/338038
Canada and the SKA from 2020 - 2030
Publisher: Zenodo
Date: 2019
The Compact X-Ray Source 1E 1547.0-5408 and the Radio Shell G327.24-0.13: A New Proposed Association between a Candidate Magnetar and a Candidate Supernova Remnant
Publisher: American Astronomical Society
Date: 10-2007
DOI: 10.1086/520526
ON THE DETECTION AND TRACKING OF SPACE DEBRIS USING THE MURCHISON WIDEFIELD ARRAY. I. SIMULATIONS AND TEST OBSERVATIONS DEMONSTRATE FEASIBILITY
Publisher: American Astronomical Society
Date: 16-09-2013
Discovery of the Luminous, Decades-long, Extragalactic Radio Transient FIRST J141918.9+394036
Publisher: American Astronomical Society
Date: 16-10-2018
A Vision for Canadian Leadership in Multi-Messenger Astrophysics in the Next Decade
Publisher: Zenodo
Date: 2019
Heartbeat of the mouse: A young radio pulsar associated with the axisymmetric nebula G359.23-0.82
Publisher: American Astronomical Society
Date: 11-2002
DOI: 10.1086/344832
Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D
Publisher: American Astronomical Society
Date: 22-06-2017
The extended X-ray emission around RRAT J1819−1458
Publisher: Oxford University Press (OUP)
Date: 04-01-2013
DOI: 10.1093/MNRAS/STS531
Future Cosmological Constraints From Fast Radio Bursts
Publisher: American Astronomical Society
Date: 26-03-2018
The Challenges of Low-Frequency Radio Polarimetry: Lessons from the Murchison Widefield Array
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.36
Abstract: We present techniques developed to calibrate and correct Murchison Widefield Array low-frequency (72–300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous ( u , v )-coverage and sensitivity to degree-scale structure that the Murchison Widefield Array provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the Murchison Widefield Array, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.
A Multifrequency Radio Study of Supernova Remnant G292.0+1.8 and Its Pulsar Wind Nebula
Publisher: American Astronomical Society
Date: 09-2003
DOI: 10.1086/376861
Shocks, Outflows and Bubbles:. New Views on Pulsars and Their Winds
Publisher: WORLD SCIENTIFIC
Date: 09-2003
The UTMOST: A Hybrid Digital Signal Processor Transforms the Molonglo Observatory Synthesis Telescope
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.39
Abstract: The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m 2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
CHANDRAANDXMMOBSERVATIONS OF THE COMPOSITE SUPERNOVA REMNANT G327.1-1.1
Publisher: American Astronomical Society
Date: 28-01-2009
Erratum: A distant extended spiral arm in the fourth quadrant of the Milky Way (The Astrophysical Journal (2004) 607 (L127))
Publisher: American Astronomical Society
Date: 20-08-2004
DOI: 10.1086/424007
Magnetically Dominated Strands of Cold Hydrogen in the Riegel-Crutcher Cloud
Publisher: American Astronomical Society
Date: 12-2006
DOI: 10.1086/508706
A Stellar Wind Bubble Coincident with the Anomalous X-Ray Pulsar 1E 1048.1-5937: Are Magnetars Formed from Massive Progenitors?
Publisher: American Astronomical Society
Date: 19-01-2005
DOI: 10.1086/428725
A Nearby Repeating Fast Radio Burst in the Direction of M81
Publisher: American Astronomical Society
Date: 31-03-2021
Fast radio burst dispersion measures and rotation measures and the origin of intergalactic magnetic fields
Publisher: Oxford University Press (OUP)
Date: 25-07-2019
Abstract: We investigate the possibility of measuring intergalactic magnetic fields using the dispersion measures and rotation measures of fast radio bursts. With Bayesian methods, we produce probability density functions for values of these measures. We distinguish between contributions from the intergalactic medium, the host galaxy, and the local environment of the progenitor. To this end, we use constrained, magnetohydrodynamic simulations of the local Universe to compute lines-of-sight integrals from the position of the Milky Way. In particular, we differentiate between predominantly astrophysical and primordial origins of magnetic fields in the intergalactic medium. We test different possible types of host galaxies and probe different distribution functions of fast radio burst progenitor locations inside the host galaxy. Under the assumption that fast radio bursts are produced by magnetars, we use analytic predictions to account for the contribution of the local environment. We find that less than 100 fast radio bursts from magnetars in stellar-wind environments hosted by starburst dwarf galaxies at redshift z ≳ 0.5 suffice to discriminate between predominantly primordial and astrophysical origins of intergalactic magnetic fields. However, this requires the contribution of the Milky Way to be removed with a precision of ≈1 rad m−2. We show the potential existence of a subset of fast radio bursts whose rotation measures carry information on the strength of the intergalactic magnetic field and its origins.
Fast Radio Burst Morphology in the First CHIME/FRB Catalog
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present a synthesis of fast radio burst (FRB) morphology (the change in flux as a function of time and frequency) as detected in the 400–800 MHz octave by the FRB project on the Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB), using events from the first CHIME/FRB catalog. The catalog consists of 62 bursts from 18 repeating sources, plus 474 one-off FRBs, detected between 2018 July 25 and 2019 July 2. We identify four observed archetypes of burst morphology (“simple broadband,” “simple narrowband,” “temporally complex,” and “downward drifting”) and describe relevant instrumental biases that are essential for interpreting the observed morphologies. Using the catalog properties of the FRBs, we confirm that bursts from repeating sources, on average, have larger widths, and we show, for the first time, that bursts from repeating sources, on average, are narrower in bandwidth. This difference could be due to beaming or propagation effects, or it could be intrinsic to the populations. We discuss potential implications of these morphological differences for using FRBs as astrophysical tools.
Constraints on large-scale magnetic fields in the intergalactic medium using cross-correlation methods
Publisher: Oxford University Press (OUP)
Date: 27-02-2021
Abstract: Large-scale coherent magnetic fields in the intergalactic medium (IGM) are presumed to play a key role in the formation and evolution of the cosmic web, and in large-scale feedback mechanisms. However, they are theorized to be extremely weak, in the nano-Gauss regime. To search for a statistical signature of these weak magnetic fields, we perform a cross-correlation between the Faraday rotation measures (RMs) of 1742 radio galaxies at z & 0.5 and large-scale structure at 0.1 & z & 0.5, as traced by 18 million optical and infrared foreground galaxies. No significant correlation signal was detected within the uncertainty limits. We are able to determine model-dependent 3σ upper limits on the parallel component of the mean magnetic field strength of filaments in the IGM of ∼30 nG for coherence scales between 1 and 2.5 Mpc, corresponding to a mean upper bound RM enhancement of ∼3.8 rad m−2 due to filaments along all probed sightlines. These upper bounds are consistent with upper bounds found previously using other techniques. Our method can be used to further constrain intergalactic magnetic fields with upcoming future radio polarization surveys.
No Evidence for Galactic Latitude Dependence of the Fast Radio Burst Sky Distribution
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We investigate whether the sky rate of fast radio bursts (FRBs) depends on Galactic latitude using the first catalog of FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project. We first select CHIME/FRB events above a specified sensitivity threshold in consideration of the radiometer equation, and then we compare these detections with the expected cumulative time-weighted exposure using Anderson–Darling and Kolmogorov–Smirnov tests. These tests are consistent with the null hypothesis that FRBs are distributed without Galactic latitude dependence ( p -values distributed from 0.05 to 0.99, depending on completeness threshold). Additionally, we compare rates in intermediate latitudes (∣ b ∣ 15°) with high latitudes using a Bayesian framework, treating the question as a biased coin-flipping experiment–again for a range of completeness thresholds. In these tests the isotropic model is significantly favored (Bayes factors ranging from 3.3 to 14.2). Our results are consistent with FRBs originating from an isotropic population of extragalactic sources.
Spitzer imaging and spectral mapping of the oxygen-rich supernova remnant G292.0+1.8
Publisher: American Astronomical Society
Date: 13-04-2012
The Asymmetric Radio Remnant of SN 1987A
Publisher: American Astronomical Society
Date: 20-04-1997
DOI: 10.1086/303917
Multi-scale feedback and feeding in the closest radio galaxy Centaurus A
Publisher: Springer Science and Business Media LLC
Date: 22-12-2021
A Southern-Sky Total Intensity Source Catalogue at 2.3 GHz from S-Band Polarisation All-Sky Survey Data
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.5
Abstract: The S -band Polarisation All-Sky Survey has observed the entire southern sky using the 64-m Parkes radio telescope at 2.3 GHz with an effective bandwidth of 184 MHz. The surveyed sky area covers all declinations δ ⩽ 0°. To analyse compact sources, the survey data have been re-processed to produce a set of 107 Stokes I maps with 10.75 arcmin resolution and the large scale emission contribution filtered out. In this paper, we use these Stokes I images to create a total intensity southern-sky extragalactic source catalogue at 2.3 GHz. The source catalogue contains 23 389 sources and covers a sky area of 16 600 deg 2 , excluding the Galactic plane for latitudes | b | 10°. Approximately, 8% of catalogued sources are resolved. S -band Polarisation All-Sky Survey source positions are typically accurate to within 35 arcsec. At a flux density of 225 mJy, the S -band Polarisation All-Sky Survey source catalogue is more than 95% complete, and ~ 94% of S -band Polarisation All-Sky Survey sources brighter than 500 mJy beam −1 have a counterpart at lower frequencies.
Bow shocks around pulsars and neutron stars
Publisher: Elsevier BV
Date: 2005
The Maunakea Spectroscopic Explorer
Publisher: Zenodo
Date: 2019
Broadband, radio spectro-polarimetric observations of radiative-mode and jet-mode AGN
Publisher: Zenodo
Date: 2016
DOI: 10.5281/ZENODO.60636
An expanding radio nebula produced by a giant flare from the magnetar SGR 1806–20
Publisher: Springer Science and Business Media LLC
Date: 04-2005
DOI: 10.1038/NATURE03498
Abstract: Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere that was recorded around the globe. Here we report the detection of a fading radio afterglow produced by this outburst, with a luminosity 500 times larger than the only other detection of a similar source. From day 6 to day 19 after the flare from SGR 1806-20, a resolved, linearly polarized, radio nebula was seen, expanding at approximately a quarter of the speed of light. To create this nebula, at least 4 x 10(43) ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles.
GLEAM: The GaLactic and Extragalactic All-Sky MWA Survey
Publisher: Cambridge University Press (CUP)
Date: 2015
DOI: 10.1017/PASA.2015.26
Abstract: GLEAM, the GaLactic and Extragalactic All-sky MWA survey, is a survey of the entire radio sky south of declination + 25° at frequencies between 72 and 231 MHz, made with the MWA using a drift scan method that makes efficient use of the MWA’s very large field-of-view. We present the observation details, imaging strategies, and theoretical sensitivity for GLEAM. The survey ran for two years, the first year using 40-kHz frequency resolution and 0.5-s time resolution the second year using 10-kHz frequency resolution and 2 s time resolution. The resulting image resolution and sensitivity depends on observing frequency, sky pointing, and image weighting scheme. At 154 MHz, the image resolution is approximately 2.5 × 2.2/cos (δ + 26.7°) arcmin with sensitivity to structures up to ~ 10° in angular size. We provide tables to calculate the expected thermal noise for GLEAM mosaics depending on pointing and frequency and discuss limitations to achieving theoretical noise in Stokes I images. We discuss challenges, and their solutions, that arise for GLEAM including ionospheric effects on source positions and linearly polarised emission, and the instrumental polarisation effects inherent to the MWA’s primary beam.
A SURVEY OF EXTRAGALACTIC FARADAY ROTATION AT HIGH GALACTIC LATITUDE: THE VERTICAL MAGNETIC FIELD OF THE MILKY WAY TOWARD THE GALACTIC POLES
Publisher: American Astronomical Society
Date: 16-04-2010
Faraday rotation at low frequencies: Magnetoionic material of the large FRII radio galaxy PKS J0636-2036
Publisher: Oxford University Press (OUP)
Date: 20-01-2018
DOI: 10.1093/MNRAS/STY171
The jet/wind outflow in Centaurus A: A local laboratory for AGN feedback
Publisher: Oxford University Press (OUP)
Date: 09-11-2018
Chandra Observation of the Globular Cluster NGC 6440 and the Nature of Cluster X-Ray Luminosity Functions
Publisher: American Astronomical Society
Date: 07-2002
DOI: 10.1086/340498
The Outer Shock of the Oxygen-Rich Supernova Remnant G292.0+1.8: Evidence for the Interaction with the Stellar Winds from Its Massive Progenitor
Publisher: American Astronomical Society
Date: 18-02-2010
The Global Magneto-ionic Medium Survey: A Faraday Depth Survey of the Northern Sky Covering 1280–1750 MHz
Publisher: American Astronomical Society
Date: 29-06-2021
Abstract: The Galactic interstellar medium hosts a significant magnetic field, which can be probed through the synchrotron emission produced from its interaction with relativistic electrons. Linearly polarized synchrotron emission is generated throughout the Galaxy and, at longer wavelengths, modified along nearly every path by Faraday rotation in the intervening magneto-ionic medium. Full characterization of the polarized emission requires wideband observations with many frequency channels. We have surveyed polarized radio emission from the Northern sky over the range 1280–1750 MHz, with channel width 236.8 kHz, using the John A. Galt Telescope (diameter 25.6 m) at the Dominion Radio Astrophysical Observatory, as part of the Global Magneto-Ionic Medium Survey. The survey covered 72% of the sky, decl. −30° to +87° at all R.A. The intensity scale was absolutely calibrated, based on the flux density and spectral index of Cygnus A. Polarization angle was calibrated using the extended polarized emission of the Fan Region. Data are presented as brightness temperatures with angular resolution 40′. Sensitivity in Stokes Q and U is 45 mK rms in a 1.18 MHz band. We have applied rotation measure synthesis to the data to obtain a Faraday depth cube of resolution 150 rad m −2 and sensitivity 3 mK rms of polarized intensity. Features in Faraday depth up to a width of 110 rad m −2 are represented. The maximum detectable Faraday depth is ±2 × 10 4 rad m −2 . The survey data are available at the Canadian Astronomy Data Centre.
Polarization Angular Spectra of Galactic Synchrotron Emission on Arcminute Scales
Publisher: American Astronomical Society
Date: 10-11-2002
DOI: 10.1086/342793
A high-resolution study of nonthermal radio and X-ray emission from supernova remnant G347.3-0.5
Publisher: American Astronomical Society
Date: 10-02-2004
DOI: 10.1086/380956
The X‐Ray Structure of the Pulsar Bow Shock G189.22+2.90 in the Supernova Remnant IC 443
Publisher: American Astronomical Society
Date: 10-09-2006
DOI: 10.1086/506246
ERRATUM: “BROADBAND RADIO POLARIMETRY AND FARADAY ROTATION OF 563 EXTRAGALACTIC RADIO SOURCES” (ApJ, 815, 1, 49)
Publisher: American Astronomical Society
Date: 04-2016
Limits on radio emission from pulsar wind nebulae
Publisher: Oxford University Press (OUP)
Date: 11-10-2000
Can Ejecta-dominated Supernova Remnants be Typed from Their X-Ray Spectra? The Case of G337.2-0.7
Publisher: American Astronomical Society
Date: 08-2006
DOI: 10.1086/505018
A model of diffuse Galactic radio emission from 10 MHz to 100 GHz
Publisher: Oxford University Press (OUP)
Date: 21-07-2008
Pulsar Wind Nebulae in EGRET Error Boxes
Publisher: Springer-Verlag
Date: 2005
Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A
Publisher: AIP
Date: 2007
DOI: 10.1063/1.3682887
Detection of a Compact X-Ray Source in the Supernova Remnant G29.6+0.1: A Variable Anomalous X-Ray Pulsar?
Publisher: American Astronomical Society
Date: 10-10-2000
DOI: 10.1086/312910
Proper-Motion Measurements of Pulsar B1951+32 in the Supernova Remnant CTB 80
Publisher: American Astronomical Society
Date: 14-02-2002
DOI: 10.1086/340002
A 22-yr southern sky survey for transient and variable radio sources using the Molonglo Observatory Synthesis Telescope
Publisher: Oxford University Press (OUP)
Date: 13-01-2011
Light Curves and Radio Structure of the 1999 September Transient Event in V4641 Sagittarii (=XTE J1819-254=SAX J1819.3-2525)
Publisher: American Astronomical Society
Date: 12-2000
DOI: 10.1086/317255
Modeling Fast Radio Burst Dispersion and Scattering Properties in the First CHIME/FRB Catalog
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We present a Monte Carlo–based population synthesis study of fast radio burst (FRB) dispersion and scattering focusing on the first catalog of sources detected with the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project. We simulate intrinsic properties and propagation effects for a variety of FRB population models and compare the simulated distributions of dispersion measures and scattering timescales with the corresponding distributions from the CHIME/FRB catalog. Our simulations confirm the results of previous population studies, which suggested that the interstellar medium of the host galaxy alone (simulated based on the NE2001 model) cannot explain the observed scattering timescales of FRBs. We therefore consider additional sources of scattering, namely, the circumgalactic medium (CGM) of intervening galaxies and the circumburst medium whose properties are modeled based on typical Galactic plane environments. We find that a population of FRBs with scattering contributed by these media is marginally consistent with the CHIME/FRB catalog. In this scenario, our simulations favor a population of FRBs offset from their galaxy centers over a population that is distributed along the spiral arms. However, if the models proposing the CGM as a source of intense scattering are incorrect, then we conclude that FRBs may inhabit environments with more extreme properties than those inferred for pulsars in the Milky Way.
A Large-Scale, Low-Frequency Murchison Widefield Array Survey of Galactic H ii Regions between 260 < l < 340
Publisher: Cambridge University Press (CUP)
Date: 2016
DOI: 10.1017/PASA.2016.19
Abstract: We have compiled a catalogue of H ii regions detected with the Murchison Widefield Array between 72 and 231 MHz. The multiple frequency bands provided by the Murchison Widefield Array allow us identify the characteristic spectrum generated by the thermal Bremsstrahlung process in H ii regions. We detect 306 H ii regions between 260° l 340° and report on the positions, sizes, peak, integrated flux density, and spectral indices of these H ii regions. By identifying the point at which H ii regions transition from the optically thin to thick regime, we derive the physical properties including the electron density, ionised gas mass, and ionising photon flux, towards 61 H ii regions. This catalogue of H ii regions represents the most extensive and uniform low frequency survey of H ii regions in the Galaxy to date.
High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta
Publisher: American Astronomical Society
Date: 19-11-2019
Discovery of a Radio Supernova Remnant and Nonthermal X-Rays Coincident with the TeV Source HESS J1813-178
Publisher: American Astronomical Society
Date: 03-08-2005
DOI: 10.1086/491471
Atomic hydrogen in a galactic center outflow
Publisher: American Astronomical Society
Date: 22-05-2013
Limits on prompt, dispersed radio pulses from gamma-ray bursts
Publisher: American Astronomical Society
Date: 04-09-2012
When Disorder Looks Like Order: A New Model to Explain Radial Magnetic Fields in Young Supernova Remnants
Publisher: American Astronomical Society
Date: 03-11-2017
Non-natives: 141 scientists object
Publisher: Springer Science and Business Media LLC
Date: 07-2011
DOI: 10.1038/475036A
The Extraordinary Linear Polarisation Structure of the Southern Centaurus A Lobe Revealed by ASKAP
Publisher: MDPI AG
Date: 29-11-2018
Abstract: We present observations of linear polarisation in the southern radio lobe of Centaurus A, conducted during commissioning of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. We used 16 antennas to observe a 30 square degree region in a single 12-h pointing over a 240 MHz band centred on 913 MHz. Our observations achieve an angular resolution of 26 × 33 arcseconds (480 parsecs), a maximum recoverable angular scale of 30 arcminutes, and a full-band sensitivity of 85 μ Jy beam − 1 . The resulting maps of polarisation and Faraday rotation are amongst the most detailed ever made for radio lobes, with order 10 5 resolution elements covering the source. We describe several as-yet unreported observational features of the lobe, including its detailed peak Faraday depth structure, and intricate networks of depolarised filaments. These results demonstrate the exciting capabilities of ASKAP for widefield radio polarimetry.
Faraday rotation from magnesium II absorbers toward polarized background radio sources
Publisher: American Astronomical Society
Date: 14-10-2014
Compact continuum source finding for next generation radio surveys
Publisher: Oxford University Press (OUP)
Date: 04-04-2012
The magnetic field of the large magellanic cloud revealed through faraday rotation
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-03-2005
Abstract: We have measured the Faraday rotation toward a large s le of polarized radio sources behind the Large Magellanic Cloud (LMC) to determine the structure of this galaxy's magnetic field. The magnetic field of the LMC consists of a coherent axisymmetric spiral of field strength ∼1 microgauss. Strong fluctuations in the magnetic field are also seen on small ( .5 parsec) and large (∼100 parsecs) scales. The large bursts of recent star formation and supernova activity in the LMC argue against standard dynamo theory, adding to the growing evidence for rapid field lification in galaxies.
Blazar jet evolution revealed by multi-epoch broad-band radio polarimetry
Publisher: Oxford University Press (OUP)
Date: 11-02-2019
DOI: 10.1093/MNRAS/STZ377
A deep search for pulsar wind nebulae using pulsar gating
Publisher: Oxford University Press (OUP)
Date: 23-09-1999
A Wide-Field, Low-Frequency Radio Survey of the Field of M31. I. Construction and Statistical Analysis of the Source Catalog
Publisher: American Astronomical Society
Date: 11-2004
DOI: 10.1086/424446
Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies
Publisher: American Astronomical Society
Date: 27-03-2017
PSR J1119–6127 and the X-ray emission from high magnetic field radio pulsars
Publisher: Springer Science and Business Media LLC
Date: 22-03-2007
A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way
Publisher: American Astronomical Society
Date: 04-05-2004
DOI: 10.1086/422031
Improving a framework for evaluating participatory science
Publisher: Center for Open Science
Date: 27-07-2022
Abstract: This article proposes improvements to an open framework for evaluating participatory science, including projects framed as citizen science. An original proposed framework, while valuable in its comprehensiveness, used problematic language that makes it unworkable in many international contexts. In countries like Australia where Indigenous data sovereignty matters profoundly, language about ‘target groups’ and ‘easing access’ to knowledge can harmfully perpetuate colonial discourses. The original proposed framework is sufficiently useful that it is worth constructively revising, so critique in this article is aimed towards collaborative progression of an open framework more suitable for international use. As well as replacing ‘target groups’ with partnership approaches, we argue that ‘easing access’ to knowledge for exploitation is a frame perpetuating the colonial doctrine of discovery, proposing recovery as an alternative aligned with several international movements for social justice and sustainability.
An X-Ray Search for Compact Central Sources in Supernova Remnants. I. SNRS G093.3+6.9, G315.4-2.3, G084.2+0.8, and G127.1+0.5
Publisher: American Astronomical Society
Date: 07-2004
DOI: 10.1086/421065
Fifteen years of high-resolution radio imaging of supernova 1987A
Publisher: AIP
Date: 2007
DOI: 10.1063/1.2803627
Polarized foreground removal at low radio frequencies using rotation measure synthesis: uncovering the signature of hydrogen reionization
Publisher: Oxford University Press (OUP)
Date: 08-09-2011
PSR J1856+0245: Arecibo Discovery of a Young, Energetic Pulsar Coincident with the TeV γ-Ray Source HESS J1857+026
Publisher: American Astronomical Society
Date: 08-07-2008
DOI: 10.1086/590908
The radio remnant of Supernova 1987A - A broader view
Publisher: Cambridge University Press (CUP)
Date: 02-2017
DOI: 10.1017/S1743921317005312
Abstract: Supernova remnants (SNRs) are powerful particle accelerators. As a supernova (SN) blast wave propagates through the circumstellar medium (CSM), electrons and protons scatter across the shock and gain energy by entrapment in the magnetic field. The accelerated particles generate further magnetic field fluctuations and local lification, leading to cosmic ray production. The wealth of data from Supernova 1987A is providing a template of the SN-CSM interaction, and an important guide to the radio detection and identification of core-collapse SNe based on their spectral properties. Thirty years after the explosion, radio observations of SNR 1987A span from 70 MHz to 700 GHz. We review extensive observing c aigns with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA), and follow-ups with other radio telescopes. Observations across the radio spectrum indicate rapid changes in the remnant morphology, while current ATCA and ALMA observations show that the SNR has entered a new evolutionary phase.
An improved map of the Galactic Faraday sky
Publisher: EDP Sciences
Date: 06-2012
A repeating fast radio burst source in a globular cluster
Publisher: Springer Science and Business Media LLC
Date: 23-02-2022
DOI: 10.1038/S41586-021-04354-W
Abstract: Fast radio bursts (FRBs) are flashes of unknown physical origin
MULTI-WAVELENGTH OBSERVATIONS OF THE RADIO MAGNETAR PSR J1622–4950 AND DISCOVERY OF ITS POSSIBLY ASSOCIATED SUPERNOVA REMNANT
Publisher: American Astronomical Society
Date: 04-05-2012
Radio Polarization from the Inner Galaxy at Arcminute Resolution
Publisher: American Astronomical Society
Date: 10-03-2001
DOI: 10.1086/319468
[ITAL]Chandra[/ITAL] Observations of the Pulsar Wind Nebula in Supernova Remnant G0.9+0.1
Publisher: American Astronomical Society
Date: 08-2001
DOI: 10.1086/322982
Erratum: “Atomic Hydrogen in a Galactic Center Outflow” (2013, ApJL, 770, L4)
Publisher: American Astronomical Society
Date: 11-10-2019
Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II. Spectroscopic and Environmental Analysis of Thorne–Żytkow Object and Super-AGB Star Candidates
Publisher: American Astronomical Society
Date: 2023
Abstract: In previous work, we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne–Żytkow objects (TŻOs red supergiants with a neutron star cores) or super-asymptotic giant branch (sAGB) stars (the most massive stars that will not undergo core collapse). This population includes HV 2112, a peculiar star previously considered in other works to be either a TŻO or high-mass asymptotic giant branch (AGB) star. Here we continue this investigation, using the kinematic and radio environments and local star formation history of these stars to place constraints on the age of the progenitor systems and the presence of past supernovae. These stars are not associated with regions of recent star formation, and we find no evidence of past supernovae at their locations. Finally, we also assess the presence of heavy elements and lithium in their spectra compared to red supergiants. We find strong absorption in Li and s-process elements compared to RSGs in most of the s le, consistent with sAGB nucleosynthesis, while HV 2112 shows additional strong lines associated with TŻO nucleosynthesis. Coupled with our previous mass estimates, the results are consistent with the stars being massive (∼4–6.5 M ⊙ ) or sAGB (∼6.5–12 M ⊙ ) stars in the thermally pulsing phase, providing crucial observations of the transition between low- and high-mass stellar populations. HV 2112 is more ambiguous it could either be a maximally massive sAGB star, or a TŻO if the minimum mass for stability extends down to ≲13 M ⊙ .
ATLAS 1.4 GHz Data Release 2 - I. Observations of the CDF-S and ELAIS-S1 fields and methods for constructing differential number counts
Publisher: Oxford University Press (OUP)
Date: 20-05-2014
DOI: 10.1093/MNRAS/STU576
Detection of a radio bridge in Abell 3667
Publisher: Oxford University Press (OUP)
Date: 02-2013
DOI: 10.1093/MNRAS/STT002
SKA and the Magnetic Universe
Publisher: Springer Berlin Heidelberg
Date: 2007
High resolution 36 GHz imaging of the supernova remnant of SN 1987A
Publisher: American Astronomical Society
Date: 09-10-2009
The POlarised GLEAM Survey (POGS) II: Results from an all-sky rotation measure synthesis survey at long wavelengths
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.20
Abstract: The low-frequency linearly polarised radio source population is largely unexplored. However, a renaissance in low-frequency polarimetry has been enabled by pathfinder and precursor instruments for the Square Kilometre Array. In this second paper from the POlarised GaLactic and Extragalactic All-Sky MWA Survey-the POlarised GLEAM Survey, or POGS-we present the results from our all-sky MWA Phase I Faraday Rotation Measure survey. Our survey covers nearly the entire Southern sky in the Declination range $-82^\\circ$ to $+30^\\circ$ at a resolution between around three and seven arcminutes (depending on Declination) using data in the frequency range 169−231 MHz. We have performed two targeted searches: the first covering 25 489 square degrees of sky, searching for extragalactic polarised sources the second covering the entire sky South of Declination $+30^\\circ$ , searching for known pulsars. We detect a total of 517 sources with 200 MHz linearly polarised flux densities between 9.9 mJy and 1.7 Jy, of which 33 are known radio pulsars. All sources in our catalogues have Faraday rotation measures in the range $-328.07$ to $+279.62$ rad m −2 . The Faraday rotation measures are broadly consistent with results from higher-frequency surveys, but with typically more than an order of magnitude improvement in the precision, highlighting the power of low-frequency polarisation surveys to accurately study Galactic and extragalactic magnetic fields. We discuss the properties of our extragalactic and known-pulsar source population, how the sky distribution relates to Galactic features, and identify a handful of new pulsar candidates among our nominally extragalactic source population.
Limits on radio emission from meteors using the MWA
Publisher: Oxford University Press (OUP)
Date: 14-04-2018
DOI: 10.1093/MNRAS/STY930
G328.4+0.2: A Large and Luminous Crab-like Supernova Remnant
Publisher: American Astronomical Society
Date: 10-10-2000
DOI: 10.1086/309522
GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey II: Galactic plane 345° <l< 67°, 180° <l< 240°
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.37
Abstract: This work makes available a further $2\,860~\text{deg}^2$ of the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey, covering half of the accessible galactic plane, across 20 frequency bands s ling 72–231 MHz, with resolution $4\,\text{arcmin}-2\,\text{arcmin}$ . Unlike previous GLEAM data releases, we used multi-scale CLEAN to better deconvolve large-scale galactic structure. For the galactic longitude ranges $345^\circ l 67^\circ$ , $180^\circ l 240^\circ$ , we provide a compact source catalogue of 22 037 components selected from a 60-MHz bandwidth image centred at 200 MHz, with RMS noise $\approx10-20\,\text{mJy}\,\text{beam}^{-1}$ and position accuracy better than 2 arcsec. The catalogue has a completeness of 50% at ${\approx}120\,\text{mJy}$ , and a reliability of 99.86%. It covers galactic latitudes $1^\circ\leq|b|\leq10^\circ$ towards the galactic centre and $|b|\leq10^\circ$ for other regions, and is available from Vizier images covering $|b|\leq10^\circ$ for all longitudes are made available on the GLEAM Virtual Observatory (VO).server and SkyView.
Near-infrared observations of rotating radio transients
Publisher: Oxford University Press (OUP)
Date: 29-06-2010
ERRATUM: “A RADIO AND OPTICAL POLARIZATION STUDY OF THE MAGNETIC FIELD IN THE SMALL MAGELLANIC CLOUD” (2008, ApJ, 688, 1029)
Publisher: American Astronomical Society
Date: 17-01-2012
Candidate radio supernova remnants observed by the GLEAM survey over 345° <l< 60° and 180° <l< 240°
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.33
Abstract: We examined the latest data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey covering 345° l 60° and 180° l 240°, using these data and that of the Widefield Infrared Survey Explorer to follow up proposed candidate Supernova Remnant (SNR) from other sources. Of the 101 candidates proposed in the region, we are able to definitively confirm ten as SNRs, tentatively confirm two as SNRs, and reclassify five as H ii regions. A further two are detectable in our images but difficult to classify the remaining 82 are undetectable in these data. We also investigated the 18 unclassified Multi-Array Galactic Plane Imaging Survey (MAGPIS) candidate SNRs, newly confirming three as SNRs, reclassifying two as H ii regions, and exploring the unusual spectra and morphology of two others.
New candidate radio supernova remnants detected in the GLEAM survey over 345° <l< 60°, 180° <l< 240°
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.34
Abstract: We have detected 27 new supernova remnants (SNRs) using a new data release of the GLEAM survey from the Murchison Widefield Array telescope, including the lowest surface brightness SNR ever detected, G 0.1 – 9.7. Our method uses spectral fitting to the radio continuum to derive spectral indices for 26/27 candidates, and our low-frequency observations probe a steeper spectrum population than previously discovered. None of the candidates have coincident WISE mid-IR emission, further showing that the emission is non-thermal. Using pulsar associations we derive physical properties for six candidate SNRs, finding G 0.1 – 9.7 may be younger than 10 kyr. Sixty per cent of the candidates subtend areas larger than 0.2 deg 2 on the sky, compared to 25% of previously detected SNRs. We also make the first detection of two SNRs in the Galactic longitude range 220°–240°.
BROADBAND SPECTRAL MODELING OF THE EXTREME GIGAHERTZ-PEAKED SPECTRUM RADIO SOURCE PKS B0008-421
Publisher: American Astronomical Society
Date: 20-08-2015
The Galactic distribution of large H I shells
Publisher: American Astronomical Society
Date: 10-10-2002
DOI: 10.1086/342470
Revealing Cosmic Magnetism with the Square Kilometre Array
Publisher: Springer New York
Date: 2008
A Candidate Relativistic Tidal Disruption Event at 340 Mpc
Publisher: American Astronomical Society
Date: 03-2023
Abstract: We present observations of an extreme radio flare, VT J024345.70-284040.08, hereafter VT J0243, from the nucleus of a galaxy with evidence for historic Seyfert activity at redshift z = 0.074. Between NRAO Very Large Array (VLA) Sky Survey observations in 1993 to VLA Sky Survey observations in 2018, VT J0243 rose from a ∼ GHz radio luminosity of ν L ν ≲ 10 38 erg s −1 to ν L ν ∼ 10 40 erg s −1 , and still continues to brighten. The radio spectral energy distribution evolution is consistent with a nascent jet that has slowed over ∼3000 days with an average 0.1 〈 β 〉 0.6. The jet is energetic (∼10 51–52 erg), and had a radius ∼0.7 pc in 2021 December. X-ray observations suggest a persistent or evolving corona, possibly associated with an accretion disk, and IR and optical observations constrain any high-energy counterpart to be sub-Eddington. VT J0243 may be an ex le of a young, off-axis radio jet from a slowly evolving tidal disruption event. Other more mysterious triggers for the accretion enhancement and jet launching are possible. In either case, VT J0243 is a unique ex le of a nascent jet, highlighting the unknown connection between supermassive black holes, the properties of their accretion flows, and jet launching.
Mapping Galactic Magnetism through Faraday Rotation of Polarized Extragalactic Sources
Publisher: Springer New York
Date: 2008
Searching for dark matter signals from local dwarf spheroidal galaxies at low radio frequencies in the GLEAM survey
Publisher: Oxford University Press (OUP)
Date: 17-03-2020
Abstract: The search for emission from weakly interacting massive particle (WIMP) dark matter annihilation and decay has become a multipronged area of research not only targeting a erse selection of astrophysical objects, but also taking advantage of the entire electromagnetic spectrum. The decay of WIMP particles into standard model particles has been suggested as a possible channel for synchrotron emission to be detected at low radio frequencies. Here, we present the stacking analysis of a s le of 33 dwarf spheroidal (dSph) galaxies with low-frequency (72–231 MHz) radio images from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. We produce radial surface brightness profiles of images centred upon each dSph galaxy with background radio sources masked. We remove 10 fields from the stacking due to contamination from either poorly subtracted, bright radio sources or strong background gradients across the field. The remaining 23 dSph galaxies are stacked in an attempt to obtain a statistical detection of any WIMP-induced synchrotron emission in these systems. We find that the stacked radial brightness profile does not exhibit a statistically significant detection above the 95 per cent confidence level of ∼1.5 mJy beam−1. This novel technique shows the potential of using low-frequency radio images to constrain fundamental properties of particle dark matter.
Discovery at the Cosmic Frontier: Canadian Astronomy Long Range Plan 2020-2030
Publisher: Zenodo
Date: 2021
The GLEAM 4-Jy (G4Jy) Sample: II. Host galaxy identification for individual sources
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.10
Abstract: The entire southern sky (Declination, $\delta 30^{\circ}$ ) has been observed using the Murchison Widefield Array (MWA), which provides radio imaging of $\sim$ 2 arcmin resolution at low frequencies (72–231 MHz). This is the GaLactic and Extragalactic All-sky MWA (GLEAM) Survey, and we have previously used a combination of visual inspection, cross-checks against the literature, and internal matching to identify the ‘brightest’ radio-sources ( $S_{\mathrm{151\,MHz}} $ Jy) in the extragalactic catalogue (Galactic latitude, $|b| ^{\circ}$ ). We refer to these 1 863 sources as the GLEAM 4-Jy (G4Jy) S le, and use radio images (of ${\leq}45$ arcsec resolution), and multi-wavelength information, to assess their morphology and identify the galaxy that is hosting the radio emission (where appropriate). Details of how to access all of the overlays used for this work are available at vw26/G4Jy . Alongside this we conduct further checks against the literature, which we document here for in idual sources. Whilst the vast majority of the G4Jy S le are active galactic nuclei with powerful radio-jets, we highlight that it also contains a nebula, two nearby, star-forming galaxies, a cluster relic, and a cluster halo. There are also three extended sources for which we are unable to infer the mechanism that gives rise to the low-frequency emission. In the G4Jy catalogue we provide mid-infrared identifications for 86% of the sources, and flag the remainder as: having an uncertain identification (129 sources), having a faint/uncharacterised mid-infrared host (126 sources), or it being inappropriate to specify a host (2 sources). For the subset of 129 sources, there is ambiguity concerning candidate host-galaxies, and this includes four sources (B0424–728, B0703–451, 3C 198, and 3C 403.1) where we question the existing identification.
A Search for Fast Radio Bursts at Low Frequencies with Murchison Widefield Array High Time Resolution Imaging
Publisher: American Astronomical Society
Date: 10-12-2015
Deep radio observations of the radio halo of the bullet cluster 1E 0657-55.8
Publisher: Oxford University Press (OUP)
Date: 16-04-2014
DOI: 10.1093/MNRAS/STU467
First limits on the 21 cm power spectrum during the Epoch of X-ray heating
Publisher: Oxford University Press (OUP)
Date: 19-05-2016
A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations
Publisher: American Astronomical Society
Date: 10-06-2008
DOI: 10.1086/527316
A radio study of the mouse, G359.23 - 0.82
Publisher: Elsevier BV
Date: 2005
X-Ray and Radio Observations of Bright GeV Sources
Publisher: Springer Netherlands
Date: 2001
Science with the Murchison Widefield Array: Phase I results and Phase II opportunities
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.41
Abstract: The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low-frequency (80–300 MHz) southern sky. Since beginning operations in mid-2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21 cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together $60+$ programs recorded 20 000 h producing 146 papers to date. In 2016, the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper, we review the major results from the prior operation of the MWA and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes but also include ideas for directions outside these categories.
Fundamental physics with the Square Kilometre Array
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2019.42
Abstract: The Square Kilometre Array (SKA) is a planned large radio interferometer designed to operate over a wide range of frequencies, and with an order of magnitude greater sensitivity and survey speed than any current radio telescope. The SKA will address many important topics in astronomy, ranging from planet formation to distant galaxies. However, in this work, we consider the perspective of the SKA as a facility for studying physics. We review four areas in which the SKA is expected to make major contributions to our understanding of fundamental physics: cosmic dawn and reionisation gravity and gravitational radiation cosmology and dark energy and dark matter and astroparticle physics. These discussions demonstrate that the SKA will be a spectacular physics machine, which will provide many new breakthroughs and novel insights on matter, energy, and spacetime.
A bright millisecond-duration radio burst from a Galactic magnetar
Publisher: Springer Science and Business Media LLC
Date: 04-11-2020
H I Shells behind the Coalsack
Publisher: American Astronomical Society
Date: 20-11-2001
DOI: 10.1086/323859
A new search for distant radio galaxies in the Southern hemisphere - II. 2.2 μm imaging*
Publisher: Oxford University Press (OUP)
Date: 21-04-2009
H I Emission and Absorption in the Southern Galactic Plane Survey*
Publisher: Cambridge University Press (CUP)
Date: 2001
DOI: 10.1071/AS01010
Abstract: We present preliminary results from the Southern Galactic Plane Survey (SGPS) Test Region and Parkes data. As part of the pilot project for the Southern Galactic Plane Survey, observations of a Test Region (325·5° ≤ l ≤ 333·5° −0·5° ≤ b ≤ 3·5°) were completed in December 1998. Single-dish observations of the full survey region (253° ≤ l ≤ 358 ° | b | ≤ 1°) with the Parkes Radio Telescope were completed in March 2000. We present a s le of SGPS H I data, with particular attention to the smallest-and largest-scale structures seen in absorption and emission, respectively. On the large scale, we detect many prominent H I shells. On the small scale, we note extremely compact, cold clouds seen in H I self-absorption. We explore how these two classes of objects probe opposite ends of the H I spatial power spectrum.
Triggered superradiance and fast radio bursts
Publisher: Oxford University Press (OUP)
Date: 10-11-2019
Two populations of gamma-ray burst radio afterglows
Publisher: American Astronomical Society
Date: 04-10-2013
CHANDRAOBSERVATIONS OF THE HIGH-MAGNETIC-FIELD RADIO PULSAR J1718–3718
Publisher: American Astronomical Society
Date: 24-05-2011
The nature of bilateral supernova remnants
Publisher: American Astronomical Society
Date: 02-1998
DOI: 10.1086/305146
Unusual Pulsed X‐Ray Emission from the Young, High Magnetic Field Pulsar PSR J1119−6127
Publisher: American Astronomical Society
Date: 09-2005
DOI: 10.1086/432032
Galactic magnetic deflections and Centaurus A as a UHECR source
Publisher: IOP Publishing
Date: 21-01-2013
Statistical techniques for detecting the intergalactic magnetic field from large samples of extragalactic Faraday rotation data
Publisher: American Astronomical Society
Date: 14-07-2014
Radio continuum and H I observations of the supernova remnant G296.8-00.3
Publisher: Oxford University Press (OUP)
Date: 06-1998
CONSTRAINING THE PROPER MOTIONS OF TWO MAGNETARS
Publisher: American Astronomical Society
Date: 15-12-2008
X‐Ray Sources and Their Optical Counterparts in the Globular Cluster M4
Publisher: American Astronomical Society
Date: 10-07-2004
DOI: 10.1086/421259
The Carina Nebula and Gum 31 molecular complex – II. The distribution of the atomic gas revealed in unprecedented detail
Publisher: Oxford University Press (OUP)
Date: 14-08-2017
First Discovery of New Pulsars and RRATs with CHIME/FRB
Publisher: American Astronomical Society
Date: 11-2021
Abstract: We report the discovery of seven new Galactic pulsars with the Canadian Hydrogen Intensity Mapping Experiment’s Fast Radio Burst (CHIME/FRB) backend. These sources were first identified via single pulses in CHIME/FRB, then followed up with CHIME/Pulsar. Four sources appear to be rotating radio transients, pulsar-like sources with occasional single-pulse emission with an underlying periodicity. Of those four sources, three have detected periods ranging from 220 ms to 2.726 s. Three sources have more persistent but still intermittent emission and are likely intermittent or nulling pulsars. We have determined phase-coherent timing solutions for the latter two. These seven sources are the first discovery of previously unknown Galactic sources with CHIME/FRB and highlight the potential of fast radio burst detection instruments to search for intermittent Galactic radio sources.
Chandra smells a RRAT
Publisher: Springer Science and Business Media LLC
Date: 15-03-2007
An Optical Bow Shock around the Nearby Millisecond Pulsar J2124-3358
Publisher: American Astronomical Society
Date: 12-2002
DOI: 10.1086/345750
A Comparison of Multiphase Magnetic Field Tracers in a High Galactic Latitude Region of the Filamentary Interstellar Medium
Publisher: American Astronomical Society
Date: 03-2022
Abstract: Understanding how the Galactic magnetic field threads the multiphase interstellar medium (ISM) remains a considerable challenge, as different magnetic field tracers probe dissimilar phases and field components. We search for evidence of a common magnetic field shared between the ionized and neutral ISM by comparing 1.4 GHz radio continuum polarization and H i line emission from the Galactic Arecibo L -Band Feed Array Continuum Transit Survey (GALFACTS) and Galactic Arecibo L -Band Feed Array H i (GALFA-H i ) survey, respectively. We compute the polarization gradient of the continuum emission and search for associations with diffuse/translucent H i structures. The polarization gradient is sensitive to changes in the integrated product of the thermal electron density and line-of-sight field strength ( B ∥ ) in warm ionized gas, while narrow H i structures highlight the plane-of-sky field orientation in cold neutral gas. We identified one region in the high Galactic latitude Arecibo sky, G216+26 centered on ( ℓ , b ) ∼ (216°, +26°), containing filaments in the polarization gradient that are aligned with narrow H i structures roughly parallel to the Galactic plane. We present a comparison of multiphase observations and magnetic field tracers of this region, demonstrating that the warm ionized and cold neutral media are connected likely via a common magnetic field. We quantify the physical properties of a polarization gradient filament associated with H α emission, measuring a line-of-sight field strength B ∥ = 6 ± 4 μ G and a plasma beta β = 2.1 − 2.1 + 3.1 . We discuss the lack of widespread multiphase magnetic field alignments and consider whether this region is associated with a short-timescale or physically rare phenomenon. This work highlights the utility of multitracer analyses for understanding the magnetized ISM.
A Radio Supernova Remnant Associated with the Young Pulsar J1119−6127
Publisher: American Astronomical Society
Date: 10-06-2001
DOI: 10.1086/321328
CHIME/FRB Catalog 1 Results: Statistical Cross-correlations with Large-scale Structure
Publisher: American Astronomical Society
Date: 11-2021
Abstract: The CHIME/FRB Project has recently released its first catalog of fast radio bursts (FRBs), containing 492 unique sources. We present results from angular cross-correlations of CHIME/FRB sources with galaxy catalogs. We find a statistically significant ( p -value ∼ 10 −4 , accounting for look-elsewhere factors) cross-correlation between CHIME FRBs and galaxies in the redshift range 0.3 ≲ z ≲ 0.5, in three photometric galaxy surveys: WISE × SCOS, DESI-BGS, and DESI-LRG. The level of cross-correlation is consistent with an order-one fraction of the CHIME FRBs being in the same dark matter halos as survey galaxies in this redshift range. We find statistical evidence for a population of FRBs with large host dispersion measure (∼400 pc cm −3 ) and show that this can plausibly arise from gas in large halos ( M ∼ 10 14 M ⊙ ), for FRBs near the halo center ( r ≲ 100 kpc). These results will improve in future CHIME/FRB catalogs, with more FRBs and better angular resolution.
Radio Polarimetry in the Southern Galactic Plane Survey
Publisher: Kluwer Academic Publishers
Date: 2004
Inferring the Energy and Distance Distributions of Fast Radio Bursts Using the First CHIME/FRB Catalog
Publisher: American Astronomical Society
Date: 02-2023
Abstract: Fast radio bursts (FRBs) are brief, energetic, typically extragalactic flashes of radio emission whose progenitors are largely unknown. Although studying the FRB population is essential for understanding how these astrophysical phenomena occur, such studies have been difficult to conduct without large numbers of FRBs and characterizable observational biases. Using the recently released catalog of 536 FRBs published by the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) collaboration, we present a study of the FRB population that also calibrates for selection effects. Assuming a Schechter function, we infer a characteristic energy cut-off of E char = 2.38 − 1.64 + 5.35 × 10 41 erg and a differential power-law index of γ = − 1.3 − 0.4 + 0.7 . Simultaneously, we infer a volumetric rate of [ 7.3 − 3.8 + 8.8 (stat.) − 1.8 + 2.0 ( sys . ) ] × 10 4 Gpc −3 yr −1 above a pivot energy of 10 39 erg and below a scattering timescale of 10 ms at 600 MHz, and find we cannot significantly constrain the cosmic evolution of the FRB population with star-formation rate. Modeling the host’s dispersion measure (DM) contribution as a log-normal distribution and assuming a total Galactic contribution of 80 pc cm −3 , we find a median value of DM host = 84 − 49 + 69 pc cm −3 , comparable with values typically used in the literature. Proposed models for FRB progenitors should be consistent with the energetics and abundances of the full FRB population predicted by our results. Finally, we infer the redshift distribution of FRBs detected with CHIME, which will be tested with the localizations and redshifts enabled by the upcoming CHIME/FRB Outriggers project.
Discovery of Four Isolated Millisecond Pulsars
Publisher: American Astronomical Society
Date: 20-05-1997
DOI: 10.1086/304041
MURCHISON WIDEFIELD ARRAY OBSERVATIONS OF ANOMALOUS VARIABILITY: A SERENDIPITOUS NIGHT-TIME DETECTION OF INTERPLANETARY SCINTILLATION
Publisher: American Astronomical Society
Date: 07-08-2015
SN 1987A at Radio Wavelengths
Publisher: Springer-Verlag
Date: 2005
Erratum: Visibility stacking in the quest for type Ia supernova radio emission (Astrophysical Journal Letters (2011) 735 (L35))
Publisher: American Astronomical Society
Date: 04-10-2011
Magnetic Fields and Ionized Gas in the Inner Galaxy: An Outer Scale for Turbulence and the Possible Role of H II Regions
Publisher: American Astronomical Society
Date: 10-07-2004
DOI: 10.1086/421341
Turbulent magnetic field in the H II region Sh 2–27
Publisher: EDP Sciences
Date: 07-2022
DOI: 10.1051/0004-6361/202039474
Abstract: Context. Magnetic fields in the turbulent interstellar medium (ISM) are a key element in understanding Galactic dynamics, but there are many observational challenges. One useful probe for studying the magnetic field component parallel to the line of sight (LoS) is Faraday rotation of linearly polarized radio synchrotron emission, combined with H α observations. H ii regions are the perfect laboratories to probe such magnetic fields as they are localized in space, and are well-defined sources often with known distances and measurable electron densities. We chose the H ii region Sharpless 2–27 (Sh 2–27) as it is located at intermediate latitudes ( b ~ 23°), meaning that it suffers from little LoS confusion from other sources. In addition, it has a large angular diameter (~10°), enabling us to study the properties of its magnetic field over a wide range of angular scales. Aims. By using a map of the magnetic field strength along the LoS ( B ‖ )for the first time, we investigate the basic statistical properties of the turbulent magnetic field inside Sh 2–27. We study the scaling of the magnetic field fluctuations, compare it to the Kolmogorov scaling, and attempt to find an outer scale of the turbulent magnetic field fluctuations. Methods. We used the polarized radio synchrotron emission data from the S-band Polarization All-Sky Survey (S-PASS) at 2.3 GHz, which allowed us to test the impact of Sh 2–27 on diffuse Galactic synchrotron polarization. We estimated the rotation measure (RM) caused by the H ii region, using the synchrotron polarization angle. We used the H α data from the Southern H α Sky Survey Atlas to estimate the free electron density ( n e ) in the H ii region. Using an ellipsoid model for the shape of Sh 2–27, and with the observed RM and emission measure ( EM ), we estimated the LoS averaged B ‖ for each LoS within the ellipsoid. To characterize the turbulent magnetic field fluctuations, we computed a second-order structure function of B ‖ We compared the structure function to Kolmogorov turbulence, and to simulations of Gaussian random fields processed in the same way as the observations. Results. We present the first continuous map of B ‖ computed using the diffuse polarized radio emission in Sh 2–27. We estimate the median value of n e as 7.3 ± 0.1 cm −3 , and the median value of B ‖ as −4.5 ± 0.1 µG, which is comparable to the magnetic field strength in diffuse ISM. The slope of the structure function of the estimated B ‖ -map is found to be slightly steeper than Kolmogorov, consistent with our Gaussian-random-field B ‖ simulations revealing that an input Kolmogorov slope in the magnetic field results in a somewhat steeper slope in B ‖ .These results suggest that the lower limit to the outer scale of turbulence is 10 pc in the H ii region, which is comparable to the size of the computation domain. Conclusions. The structure functions of B ‖ fluctuations in Sh 2–27 show that the magnetic field fluctuations in this H ii region are consistent with a Kolmogorov-like turbulence. Comparing the observed and simulated B ‖ structure functions results in the estimation of a lower limit to the outer scale of the turbulent magnetic field fluctuations of 10 pc, which is limited by the size of the field of view under study. This may indicate that the turbulence probed here could actually be cascading from the larger scales in the ambient medium, associated with the interstellar turbulence in the general ISM, which is illuminated by the presence of Sh 2–27.
``Missing Link'' Clouds in the Southern Galactic Plane Survey
Publisher: American Astronomical Society
Date: 20-06-2005
DOI: 10.1086/430296
Variable high-energy γ-ray emission from pulsar wind nebulae
Publisher: AIP
Date: 2001
DOI: 10.1063/1.1419470
Loops, Drips, and Walls in the Galactic Chimney GSH 277+00+36
Publisher: American Astronomical Society
Date: 10-09-2003
DOI: 10.1086/377152
Pulsed X‐Ray Emission from Pulsar A in the Double Pulsar System J0737−3039
Publisher: American Astronomical Society
Date: 12-2007
DOI: 10.1086/522298
Nondetection of a Pulsar-powered Nebula in Puppis A and the Implications for the Nature of the Radio-quiet Neutron Star RX J0822-4300
Publisher: American Astronomical Society
Date: 07-2000
DOI: 10.1086/312750
Late-time Evolution and Modeling of the Off-axis Gamma-Ray Burst Candidate FIRST J141918.9+394036
Publisher: American Astronomical Society
Date: 2022
Abstract: We present new radio and optical data, including very-long-baseline interferometry, as well as archival data analysis, for the luminous, decades-long radio transient FIRST J141918.9+394036. The radio data reveal a synchrotron self-absorption peak around 0.3 GHz and a radius of around 1.3 mas (0.5 pc) 26 yr post-discovery, indicating a blastwave energy ∼5 × 10 50 erg. The optical spectrum shows a broad [O iii ] λ 4959,5007 emission line that may indicate collisional excitation in the host galaxy, but its association with the transient cannot be ruled out. The properties of the host galaxy are suggestive of a massive stellar progenitor that formed at low metallicity. Based on the radio light curve, blastwave velocity, energetics, nature of the host galaxy and transient rates, we find that the properties of J1419+3940 are most consistent with long gamma-ray burst (LGRB) afterglows. Other classes of (optically discovered) stellar explosions as well as neutron star mergers are disfavored, and invoking any exotic scenario may not be necessary. It is therefore likely that J1419+3940 is an off-axis LGRB afterglow (as suggested by Law et al. and Marcote et al.), and under this premise the inverse beaming fraction is found to be f b − 1 ≃ 280 − 200 + 700 , corresponding to an average jet half-opening angle θ j ≃ 5 − 2 + 4 degrees (68% confidence), consistent with previous estimates. From the volumetric rate we predict that surveys with the Very Large Array, Australian Square Kilometre Array Pathfinder, and MeerKAT will find a handful of J1419+3940-like events over the coming years.
Probes of turbulent driving mechanisms in molecular clouds from fluctuations in synchrotron intensity
Publisher: Oxford University Press (OUP)
Date: 20-12-2016
An Eccentric Binary Millisecond Pulsar in the Galactic Plane
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-06-2008
Abstract: Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric ( e = 0.44) 95-day orbit around a solar mass ( \\batchmode \\documentclass[fleqn,10pt,legalpaper]{article} \\usepackage{amssymb} \\usepackage{amsfonts} \\usepackage{amsmath} \\pagestyle{empty} \\begin{document} \\(\\mathrm{M}_{{\\odot}}\\) \\end{document} ) companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk, or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 ± 0.04 \\batchmode \\documentclass[fleqn,10pt,legalpaper]{article} \\usepackage{amssymb} \\usepackage{amsfonts} \\usepackage{amsmath} \\pagestyle{empty} \\begin{document} \\(\\mathrm{M}_{{\\odot}}\\) \\end{document} , an unusually high value.
Calibration and Stokes Imaging with Full Embedded Element Primary Beam Model for the Murchison Widefield Array
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.54
Abstract: The Murchison Widefield Array (MWA), located in Western Australia, is one of the low-frequency precursors of the international Square Kilometre Array (SKA) project. In addition to pursuing its own ambitious science programme, it is also a testbed for wide range of future SKA activities ranging from hardware, software to data analysis. The key science programmes for the MWA and SKA require very high dynamic ranges, which challenges calibration and imaging systems. Correct calibration of the instrument and accurate measurements of source flux densities and polarisations require precise characterisation of the telescope’s primary beam. Recent results from the MWA GaLactic Extragalactic All-sky Murchison Widefield Array (GLEAM) survey show that the previously implemented Average Embedded Element (AEE) model still leaves residual polarisations errors of up to 10–20% in Stokes Q. We present a new simulation-based Full Embedded Element (FEE) model which is the most rigorous realisation yet of the MWA’s primary beam model. It enables efficient calculation of the MWA beam response in arbitrary directions without necessity of spatial interpolation. In the new model, every dipole in the MWA tile (4 × 4 bow-tie dipoles) is simulated separately, taking into account all mutual coupling, ground screen, and soil effects, and therefore accounts for the different properties of the in idual dipoles within a tile. We have applied the FEE beam model to GLEAM observations at 200–231 MHz and used false Stokes parameter leakage as a metric to compare the models. We have determined that the FEE model reduced the magnitude and declination-dependent behaviour of false polarisation in Stokes Q and V while retaining low levels of false polarisation in Stokes U.
The Interstellar Medium around the Supernova Remnant G320.4-1.2
Publisher: American Astronomical Society
Date: 2002
DOI: 10.1086/324736
Southern Galactic Plane Survey Measurements of the Spatial Power Spectrum of Interstellar Hi in the Inner Galaxy
Publisher: American Astronomical Society
Date: 11-2001
DOI: 10.1086/323409
X‐Ray Observations of the New Pulsar–Supernova Remnant System PSR J1119−6127 and Supernova Remnant G292.2−0.5
Publisher: American Astronomical Society
Date: 10-06-2001
DOI: 10.1086/321340
Evolution of the Radio Remnant of SN 1987A: 1990-2001
Publisher: Cambridge University Press (CUP)
Date: 2002
DOI: 10.1071/AS01042
Abstract: The development of the radio remnant of SN 1987A has been followed using the Australia Telescope Compact Array since its first detection in 1990 August. The remnant has been observed at four frequencies, 1.4, 2.4, 4.8, and 8.6 GHz, at intervals of 4–6 weeks since the first detection. These data are combined with the 843 MHz data set of Ball et al. (2001) obtained at Molonglo Observatory to study the spectral and temporal variations of the emission. These observations show that the remnant continues to increase in brightness, with a larger rate of increase at recent times. They also show that the radio spectrum is becoming flatter, with the spectral index changing from −0.97 to −0.88 over the 11 years. In addition, at roughly yearly intervals since 1992, the remnant has been imaged at 9 GHz using super-resolution techniques to obtain an effective synthesised beamwidth of about 0″.5. The imaging observations confirm the shell morphology of the radio remnant and show that it continues to expand at ˜3000 km s −1 . The bright regions of radio emission seen on the limb of the shell do not appear to be related to the optical hot spots which have subsequently appeared in surrounding circumstellar material.
Long-term Monitoring of Molonglo Calibrators
Publisher: Cambridge University Press (CUP)
Date: 2000
DOI: 10.1071/AS00072
Abstract: Before and after every 12 hour synthesis observation, the Molonglo Observatory Synthesis Telescope (MOST) measures the flux densities of ∼5 compact extragalactic radio sources, chosen from a list of 55 calibrators. From 1984 to 1996, the MOST made some 58,000 such measurements. We have developed an algorithm to process this dataset to produce a light curve for each source spanning this thirteen-year period. We find that 18 of the 55 calibrators are variable, on time scales between one and ten years. There is the tendency for sources closer to the Galactic Plane to be more likely to vary, which suggests that the variability is a result of refractive scintillation in the Galactic interstellar medium. The sources with the flattest radio spectra show the highest levels of variability, an effect possibly resulting from differing orientations of the radio axes to the line of sight.
The POlarised GLEAM Survey (POGS) I: First results from a low-frequency radio linear polarisation survey of the southern sky
Publisher: Cambridge University Press (CUP)
Date: 2018
DOI: 10.1017/PASA.2018.39
Abstract: The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical s les. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (the precursor for the low-frequency component of the Square Kilometre Array) offers an opportunity to probe the physics of radio sources at very low radio frequencies. In this paper, we present a catalogue of linearly polarised sources detected at 216 MHz, using data from the Galactic and Extragalactic All-sky Murchison Widefield Array survey. Our catalogue covers the Declination range –17° to –37° and 24 h in Right Ascension, at a resolution of around 3 arcminutes. We detect 81 sources (including both a known pulsar and a new pulsar candidate) with linearly polarised flux densities in excess of 18 mJy across a survey area of approximately 6 400 deg 2 , corresponding to a surface density of 1 source per 79 deg 2 . The level of Faraday rotation measured for our sources is broadly consistent with those recovered at higher frequencies, with typically more than an order of magnitude improvement in the uncertainty compared to higher-frequency measurements. However, our catalogue is likely incomplete at low Faraday rotation measures, due to our practice of excluding sources in the region where instrumental leakage appears. The majority of sources exhibit significant depolarisation compared to higher frequencies however, a small sub-s le repolarise at 216 MHz. We also discuss the polarisation properties of four nearby, large-angular-scale radio galaxies, with a particular focus on the giant radio galaxy ESO 422–G028, in order to explain the striking differences in polarised morphology between 216 MHz and 1.4 GHz.
CHIME/FRB Discovery of Eight New Repeating Fast Radio Burst Sources
Publisher: American Astronomical Society
Date: 31-10-2019
The Phase II Murchison Widefield Array: Design overview
Publisher: Cambridge University Press (CUP)
Date: 2018
DOI: 10.1017/PASA.2018.37
Abstract: We describe the motivation and design details of the ‘Phase II’ upgrade of the Murchison Widefield Array radio telescope. The expansion doubles to 256 the number of antenna tiles deployed in the array. The new antenna tiles enhance the capabilities of the Murchison Widefield Array in several key science areas. Seventy-two of the new tiles are deployed in a regular configuration near the existing array core. These new tiles enhance the surface brightness sensitivity of the array and will improve the ability of the Murchison Widefield Array to estimate the slope of the Epoch of Reionisation power spectrum by a factor of ∼3.5. The remaining 56 tiles are deployed on long baselines, doubling the maximum baseline of the array and improving the array u, v coverage. The improved imaging capabilities will provide an order of magnitude improvement in the noise floor of Murchison Widefield Array continuum images. The upgrade retains all of the features that have underpinned the Murchison Widefield Array’s success (large field of view, snapshot image quality, and pointing agility) and boosts the scientific potential with enhanced imaging capabilities and by enabling new calibration strategies.
A BROADBAND STUDY OF THE EMISSION FROM THE COMPOSITE SUPERNOVA REMNANT MSH 11-62
Publisher: American Astronomical Society
Date: 30-03-2012
Nonthermal X-Ray Emission from the Shell-Type Supernova Remnant G347.3-0.5
Publisher: American Astronomical Society
Date: 11-1999
DOI: 10.1086/307893
Perspectives of scholars on the origin, spread and consequences of COVID-19 are diverse but not polarized
Publisher: Springer Science and Business Media LLC
Date: 15-06-2022
DOI: 10.1057/S41599-022-01216-2
Abstract: The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2, has devastated every sphere of human society. Governments around the world implemented unprecedented policies designed to slow the spread of the disease and assistance to cope with its impacts. Such policies, however, are short-term and debates have ensued about what broader policies are needed in the post-COVID-19 era to ensure societies are better prepared for future pandemics. Public opinion concerning COVID-19 and the post-COVID-19 era is erse, and the patterns in opinion are not well documented. Here we synthesized the opinions of 3731 research scholars throughout the world based on a survey. The highest consensus among respondents concerned the need for improving public health infrastructure and delivering economic support, whereas agreement concerning ecological aspects was low. The survey revealed three dimensions of thinking about COVID-19. The first dimension relates to public health and has widespread support. The second dimension relates to science-led policy development focusing on social justice and environmental governance, covering components of both ecology and economy. The third dimension covers the role of nature conservation in reducing the risk of pandemics. Although opinions differed with age, country of citizenship, and level of education, there is strong agreement on the need for global health equity and science-led public policy.
In situ measurement of MWA primary beam variation using ORBCOMM
Publisher: Cambridge University Press (CUP)
Date: 2018
DOI: 10.1017/PASA.2018.30
Abstract: We provide the first in situ measurements of antenna element beam shapes of the Murchison Widefield Array. Most current processing pipelines use an assumed beam shape, which can cause absolute and relative flux density errors and polarisation ‘leakage’. Understanding the primary beam is then of paramount importance, especially for sensitive experiments such as a measurement of the 21-cm line from the epoch of reionisation, where the calibration requirements are so extreme that tile to tile beam variations may affect our ability to make a detection. Measuring the primary beam shape from visibilities is challenging, as multiple instrumental, atmospheric, and astrophysical factors contribute to uncertainties in the data. Building on the methods of Neben et al. [Radio Sci., 50, 614], we tap directly into the receiving elements of the telescope before any digitisation or correlation of the signal. Using ORBCOMM satellite passes we are able to produce all-sky maps for four separate tiles in the XX polarisation. We find good agreement with the beam model of Sokolowski et al. [2017, PASA, 34, e062], and clearly observe the effects of a missing dipole from a tile in one of our beam maps. We end by motivating and outlining additional on-site experiments.
The 69 Millisecond Radio Pulsar near the Supernova Remnant RCW 103
Publisher: American Astronomical Society
Date: 20-08-1998
DOI: 10.1086/311550
The Very Young Radio Pulsar J1357-6429
Publisher: American Astronomical Society
Date: 08-07-2004
DOI: 10.1086/423620
DISCOVERY OF EXTENDED X-RAY EMISSION AROUND THE HIGHLY MAGNETIC RRAT J1819-1458
Publisher: American Astronomical Society
Date: 09-2009
Two Young Radio Pulsars Coincident with EGRET Sources
Publisher: American Astronomical Society
Date: 05-2001
DOI: 10.1086/320264
The future of Canada's radio astronomy
Publisher: Springer Science and Business Media LLC
Date: 02-11-2017
Chandra monitoring of the candidate anomalous X-ray pulsar AX J1845.0-0258
Publisher: Springer Netherlands
Date: 2007
Antisymmetry in the Faraday rotation sky caused by a nearby magnetized bubble
Publisher: American Astronomical Society
Date: 28-10-2010
A Wide-Field, Low-Frequency Radio Image of the Field of M31. II. Source Classification and Discussion
Publisher: American Astronomical Society
Date: 08-2005
DOI: 10.1086/431363
Arecibo Pulsar Survey Using ALFA. II. The Young, Highly Relativistic Binary Pulsar J1906+0746
Publisher: American Astronomical Society
Date: 20-03-2006
DOI: 10.1086/499918
The Next Generation Very Large Array
Publisher: Zenodo
Date: 2019
The Reacceleration of the Shock Wave in the Radio Remnant of SN 1987A
Publisher: American Astronomical Society
Date: 31-10-2018
Magnetic Fields in Supernova Remnants and Pulsar-Wind Nebulae
Publisher: Springer Science and Business Media LLC
Date: 16-04-2011
The Duck Redux: An Improved Proper‐Motion Upper Limit for the Pulsar B1757−24 near the Supernova Remnant G5.4–1.2
Publisher: American Astronomical Society
Date: 12-2006
DOI: 10.1086/507938
Erratum: Galactic synchrotron emissivity measurements between 250° < l < 355° from the GLEAM survey with the MWA
Publisher: Oxford University Press (OUP)
Date: 17-08-2017
Discovery of a new pulsar wind nebula in the large magellanic cloud
Publisher: American Astronomical Society
Date: 11-08-2003
DOI: 10.1086/378687
Three-dimensional hydrodynamic simulations of asymmetric pulsar wind bow shocks
Publisher: Oxford University Press (OUP)
Date: 21-01-2007
A high reliability survey of discrete Epoch of Reionization foreground sources in the MWA EoR0 field
Publisher: Oxford University Press (OUP)
Date: 08-07-2016
Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB ∼ 180916.J0158+65
Publisher: American Astronomical Society
Date: 06-10-2020
Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA and ATCA
Publisher: American Astronomical Society
Date: 10-11-2014
S-PASS/ATCA: A window on the magnetic universe in the Southern hemisphere
Publisher: Oxford University Press (OUP)
Date: 10-01-2019
DOI: 10.1093/MNRAS/STZ092
Energizing the Disk-Halo at Different Redshifts: Linking the cosmic evolution of gas and star formation in galaxies
Publisher: EDP Sciences
Date: 2012
DOI: 10.1051/EAS/1256019
The 154 MHz radio sky observed by the Murchison Widefield Array: Noise, confusion, and first source count analyses
Publisher: Oxford University Press (OUP)
Date: 12-04-2016
DOI: 10.1093/MNRAS/STW823
A giant γ-ray flare from the magnetar SGR 1806–20
Publisher: Springer Science and Business Media LLC
Date: 04-2005
DOI: 10.1038/NATURE03525
Abstract: Two classes of rotating neutron stars-soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars-are magnetars, whose X-ray emission is powered by a very strong magnetic field (B approximately 10(15) G). SGRs occasionally become 'active', producing many short X-ray bursts. Extremely rarely, an SGR emits a giant flare with a total energy about a thousand times higher than in a typical burst. Here we report that SGR 1806-20 emitted a giant flare on 27 December 2004. The total (isotropic) flare energy is 2 x 10(46) erg, which is about a hundred times higher than the other two previously observed giant flares. The energy release probably occurred during a catastrophic reconfiguration of the neutron star's magnetic field. If the event had occurred at a larger distance, but within 40 megaparsecs, it would have resembled a short, hard gamma-ray burst, suggesting that flares from extragalactic SGRs may form a subclass of such bursts.
The CHIME Fast Radio Burst Project: System Overview
Publisher: American Astronomical Society
Date: 09-08-2018
NEW CONSTRAINTS ON THE GALACTIC HALO MAGNETIC FIELD USING ROTATION MEASURES OF EXTRAGALACTIC SOURCES TOWARD THE OUTER GALAXY
Publisher: American Astronomical Society
Date: 23-07-2012
Constraints on the Distance to SGR 1806-20 from H I Absorption
Publisher: American Astronomical Society
Date: 17-08-2005
DOI: 10.1086/496879
The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD)
Publisher: Zenodo
Date: 2019
X-Ray Detection of Pulsar PSR B1757-24 and Its Nebular Tail
Publisher: American Astronomical Society
Date: 12-2001
DOI: 10.1086/324757
Advanced Diagnostics for the Study of Linearly Polarized Emission. II. Application to Diffuse Interstellar Radio Synchrotron Emission
Publisher: American Astronomical Society
Date: 02-03-2018
Deep Chandra Observation of the Pulsar Wind Nebula Powered by Pulsar PSR J1846-0258 in the Supernova Remnant Kes 75
Publisher: American Astronomical Society
Date: 10-10-2008
DOI: 10.1086/591146
[ITAL]XMM-Newton[/ITAL] Spectroscopy of the Accretion-driven Millisecond X-Ray Pulsar XTE J1751−305 in Outburst
Publisher: American Astronomical Society
Date: 02-2003
DOI: 10.1086/368105
Discovery of PSR J0523-7125 as a Circularly Polarized Variable Radio Source in the Large Magellanic Cloud
Publisher: American Astronomical Society
Date: 05-2022
Abstract: We report the discovery of a highly circularly polarized, variable, steep-spectrum pulsar in the Australian Square Kilometre Array Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey. The pulsar is located about 1° from the center of the Large Magellanic Cloud, and has a significant fractional circular polarization of ∼20%. We discovered pulsations with a period of 322.5 ms, dispersion measure (DM) of 157.5 pc cm −3 , and rotation measure (RM) of +456 rad m −2 using observations from the MeerKAT and the Parkes telescopes. This DM firmly places the source, PSR J0523−7125, in the Large Magellanic Cloud (LMC). This RM is extreme compared to other pulsars in the LMC (more than twice that of the largest previously reported one). The average flux density of ∼1 mJy at 1400 MHz and ∼25 mJy at 400 MHz places it among the most luminous radio pulsars known. It likely evaded previous discovery because of its very steep radio spectrum (spectral index α ≈ −3, where S ν ∝ ν α ) and broad pulse profile (duty cycle ≳35%). We discuss implications for searches for unusual radio sources in continuum images, as well as extragalactic pulsars in the Magellanic Clouds and beyond. Our result highlighted the possibility of identifying pulsars, especially extreme pulsars, from radio continuum images. Future large-scale radio surveys will give us an unprecedented opportunity to discover more pulsars and potentially the most distant pulsars beyond the Magellanic Clouds.
Observed Faraday Effects in Damped LyαAbsorbers and Lyman Limit Systems: The Magnetized Environment of Galactic Building Blocks at Redshift = 2
Publisher: American Astronomical Society
Date: 25-05-2017
Detection of a coherent magnetic field in the Magellanic Bridge through Faraday rotation
Publisher: Oxford University Press (OUP)
Date: 24-01-2017
DOI: 10.1093/MNRAS/STX206
Detection of Repeating FRB 180916.J0158+65 Down to Frequencies of 300 MHz
Publisher: American Astronomical Society
Date: 22-06-2020
Complex Faraday depth structure of active galactic nuclei as revealed by broad-band radio polarimetry
Publisher: Oxford University Press (OUP)
Date: 28-02-2012
A multifrequency radio continuum study of the Magellanic Clouds – I. Overall structure and star formation rates
Publisher: Oxford University Press (OUP)
Date: 23-07-2018
Dynamical Formation of Close Binary Systems in Globular Clusters
Publisher: American Astronomical Society
Date: 13-06-2003
DOI: 10.1086/377074
Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.4
Abstract: We present the first Faraday rotation measure (RM) grid study of an in idual low-mass cluster—the Fornax cluster—which is presently undergoing a series of mergers. Exploiting commissioning data for the POlarisation Sky Survey of the Universe’s Magnetism (POSSUM) covering a ${\\sim}34$ square degree sky area using the Australian Square Kilometre Array Pathfinder (ASKAP), we achieve an RM grid density of ${\\sim}25$ RMs per square degree from a 280-MHz band centred at 887 MHz, which is similar to expectations for forthcoming GHz-frequency ${\\sim}3\\pi$ -steradian sky surveys. These data allow us to probe the extended magnetoionic structure of the cluster and its surroundings in unprecedented detail. We find that the scatter in the Faraday RM of confirmed background sources is increased by $16.8\\pm2.4$ rad m −2 within 1 $^\\circ$ (360 kpc) projected distance to the cluster centre, which is 2–4 times larger than the spatial extent of the presently detectable X-ray-emitting intracluster medium (ICM). The mass of the Faraday-active plasma is larger than that of the X-ray-emitting ICM and exists in a density regime that broadly matches expectations for moderately dense components of the Warm-Hot Intergalactic Medium. We argue that forthcoming RM grids from both targeted and survey observations may be a singular probe of cosmic plasma in this regime. The morphology of the global Faraday depth enhancement is not uniform and isotropic but rather exhibits the classic morphology of an astrophysical bow shock on the southwest side of the main Fornax cluster, and an extended, swept-back wake on the northeastern side. Our favoured explanation for these phenomena is an ongoing merger between the main cluster and a subcluster to the southwest. The shock’s Mach angle and stand-off distance lead to a self-consistent transonic merger speed with Mach 1.06. The region hosting the Faraday depth enhancement also appears to show a decrement in both total and polarised radio emission compared to the broader field. We evaluate cosmic variance and free-free absorption by a pervasive cold dense gas surrounding NGC 1399 as possible causes but find both explanations unsatisfactory, warranting further observations. Generally, our study illustrates the scientific returns that can be expected from all-sky grids of discrete sources generated by forthcoming all-sky radio surveys.
A catalogue of radio supernova remnants and candidate supernova remnants in the EMU/POSSUM Galactic pilot field
Publisher: Oxford University Press (OUP)
Date: 28-06-2023
Abstract: We use data from the pilot observations of the EMU/POSSUM surveys to study the ‘missing supernova remnant (SNR) problem’, the discrepancy between the number of Galactic SNRs that have been observed, and the number that are estimated to exist. The Evolutionary Map of the Universe (EMU) and the Polarization Sky Survey of the Universe’s Magnetism (POSSUM) are radio sky surveys that are conducted using the Australian Square Kilometre Array Pathfinder (ASKAP). We report on the properties of seven known SNRs in the joint Galactic pilot field, with an approximate longitude and latitude of 323° ≤ l ≤ 330° and −4° ≤ b ≤ 2°, respectively, and identify 21 SNR candidates. Of these, four have been previously identified as SNR candidates, three were previously listed as a single SNR, 13 have not been previously studied, and one has been studied in the infrared. These are the first discoveries of Galactic SNR candidates with EMU/POSSUM and, if confirmed, they will increase the SNR density in this field by a factor of 4. By comparing our SNR candidates to the known Galactic SNR population, we demonstrate that many of these sources were likely missed in previous surveys due to their small angular size and/or low surface brightness. We suspect that there are SNRs in this field that remain undetected due to limitations set by the local background and confusion with other radio sources. The results of this paper demonstrate the potential of the full EMU/POSSUM surveys to uncover more of the missing Galactic SNR population.
Science with the Large Synoptic Survey Telescope
Publisher: Zenodo
Date: 2019
Broadband radio polarimetry of Fornax A. I. Depolarized patches generated by advected thermal material from NGC 1316
Publisher: American Astronomical Society
Date: 06-03-2018
A Neutral Hydrogen Self-Absorption Cloud in the Southern Galactic Plane Survey
Publisher: American Astronomical Society
Date: 12-2003
DOI: 10.1086/379114
Observations of PSR J2021+3651 and its X‐Ray Pulsar Wind Nebula G75.2+0.1
Publisher: American Astronomical Society
Date: 09-2004
DOI: 10.1086/422408
Constraints on the distribution and energetics of fast radio bursts using cosmological hydrodynamic simulations
Publisher: Oxford University Press (OUP)
Date: 30-06-2015
RADIO SYNCHROTRON FLUCTUATION STATISTICS AS A PROBE OF MAGNETIZED INTERSTELLAR TURBULENCE
Publisher: American Astronomical Society
Date: 27-04-2016
IRAS 15099–5856: REMARKABLE MID-INFRARED SOURCE WITH PROMINENT CRYSTALLINE SILICATE EMISSION EMBEDDED IN THE SUPERNOVA REMNANT MSH15–52
Publisher: American Astronomical Society
Date: 06-04-2011
Differences in Faraday Rotation between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields
Publisher: American Astronomical Society
Date: 18-06-2019
PROPERTIES OF INTERSTELLAR TURBULENCE FROM GRADIENTS OF LINEAR POLARIZATION MAPS
Publisher: American Astronomical Society
Date: 02-04-2012
No Low-frequency Emission from Extremely Bright Fast Radio Bursts
Publisher: American Astronomical Society
Date: 29-10-2018
XMM‐NewtonObservations of PSR B1823−13: An Asymmetric Synchrotron Nebula around a Vela‐like Pulsar
Publisher: American Astronomical Society
Date: 05-2003
DOI: 10.1086/368356
Anomalous X-Ray Pulsars and Soft Gamma-Ray Repeaters in Supernova Remnants
Publisher: American Astronomical Society
Date: 10-2001
DOI: 10.1086/322358
Automatic classification of time-variable x-ray sources
Publisher: American Astronomical Society
Date: 10-04-2014
CHIME/FRB Detection of the Original Repeating Fast Radio Burst Source FRB 121102
Publisher: American Astronomical Society
Date: 05-09-2019
Spitzer Space Telescope Detection of the Young Supernova Remnant 1E 0102.2-7219
Publisher: American Astronomical Society
Date: 04-10-2005
DOI: 10.1086/497985
Chandra smells a RRAT
Publisher: Springer Netherlands
Date: 2007
High-Resolution X-Ray Imaging of Supernova Remnant 1987A
Publisher: American Astronomical Society
Date: 02-11-2009
Galactic synchrotron distribution derived from 152 H ii region absorption features in the full GLEAM survey
Publisher: Oxford University Press (OUP)
Date: 29-06-2018
PSR J1119─6127 and the X-ray emission from high magnetic field radio pulsars
Publisher: Springer Netherlands
Date: 2007
Multiwavelength Constraints on the Origin of a Nearby Repeating Fast Radio Burst Source in a Globular Cluster
Publisher: Research Square Platform LLC
Date: 19-09-2023
Interacting large-scale magnetic fields and ionized gas in the W50/SS433 system
Publisher: Oxford University Press (OUP)
Date: 22-02-2017
DOI: 10.1093/MNRAS/STX338
X-Ray Timing, Spectroscopy, and Photometry of the Anomalous X-Ray Pulsar Candidate CXOU J010043.1-721134
Publisher: American Astronomical Society
Date: 22-06-2005
DOI: 10.1086/432441
Broadband Observations and Modeling of the Shell-Type Supernova Remnant G347.3-0.5
Publisher: American Astronomical Society
Date: 10-12-2001
DOI: 10.1086/323687
A search for long-time-scale, low-frequency radio transients
Publisher: Oxford University Press (OUP)
Date: 30-11-2016
Limits on Fast Radio Bursts and other transient sources at 182 MHz using the Murchison Widefield Array
Publisher: Oxford University Press (OUP)
Date: 03-2016
DOI: 10.1093/MNRAS/STW451
The Karl G. Jansky Very Large Array Sky Survey (VLASS). Science Case and Survey Design
Publisher: IOP Publishing
Date: 28-01-2020
A precision multi-band two-epoch photometric catalog of 44 million sources in the northern SKY from a combination of the USNO-B and Sloan Digital Sky survey catalogs
Publisher: American Astronomical Society
Date: 14-11-2013
FARADAY ROTATION OF THE SUPERNOVA REMNANT G296.5+10.0: EVIDENCE FOR A MAGNETIZED PROGENITOR WIND
Publisher: American Astronomical Society
Date: 11-03-2010
The GLEAM 4-Jy (G4Jy) Sample: I. Definition and the catalogue
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.9
Abstract: The Murchison Widefield Array (MWA) has observed the entire southern sky (Declination, $\delta 30^{\circ}$ ) at low radio frequencies, over the range 72–231MHz. These observations constitute the GaLactic and Extragalactic All-sky MWA (GLEAM) Survey, and we use the extragalactic catalogue (EGC) (Galactic latitude, $|b| ^{\circ}$ ) to define the GLEAM 4-Jy (G4Jy) S le. This is a complete s le of the ‘brightest’ radio sources ( $S_{\textrm{151\,MHz}} \,\text{Jy}$ ), the majority of which are active galactic nuclei with powerful radio jets. Crucially, low-frequency observations allow the selection of such sources in an orientation-independent way (i.e. minimising the bias caused by Doppler boosting, inherent in high-frequency surveys). We then use higher-resolution radio images, and information at other wavelengths, to morphologically classify the brightest components in GLEAM. We also conduct cross-checks against the literature and perform internal matching, in order to improve s le completeness (which is estimated to be $ .5$ %). This results in a catalogue of 1863 sources, making the G4Jy S le over 10 times larger than that of the revised Third Cambridge Catalogue of Radio Sources (3CRR $S_{\textrm{178\,MHz}} .9\,\text{Jy}$ ). Of these G4Jy sources, 78 are resolved by the MWA (Phase-I) synthesised beam ( $\sim2$ arcmin at 200MHz), and we label 67% of the s le as ‘single’, 26% as ‘double’, 4% as ‘triple’, and 3% as having ‘complex’ morphology at $\sim1\,\text{GHz}$ (45 arcsec resolution). We characterise the spectral behaviour of these objects in the radio and find that the median spectral index is $\alpha=-0.740 \pm 0.012$ between 151 and 843MHz, and $\alpha=-0.786 \pm 0.006$ between 151MHz and 1400MHz (assuming a power-law description, $S_{\nu} \propto \nu^{\alpha}$ ), compared to $\alpha=-0.829 \pm 0.006$ within the GLEAM band. Alongside this, our value-added catalogue provides mid-infrared source associations (subject to 6” resolution at 3.4 $\mu$ m) for the radio emission, as identified through visual inspection and thorough checks against the literature. As such, the G4Jy S le can be used as a reliable training set for cross-identification via machine-learning algorithms. We also estimate the angular size of the sources, based on their associated components at $\sim1\,\text{GHz}$ , and perform a flux density comparison for 67 G4Jy sources that overlap with 3CRR. Analysis of multi-wavelength data, and spectral curvature between 72MHz and 20GHz, will be presented in subsequent papers, and details for accessing all G4Jy overlays are provided at vw26/G4Jy .
FIRST J153350.8+272729: The Radio Afterglow of a Decades-old Tidal Disruption Event
Publisher: American Astronomical Society
Date: 02-2022
Abstract: We present the discovery of the fading radio transient FIRST J153350.8+272729. The source had a maximum observed 5 GHz radio luminosity of 8 × 10 39 erg s −1 in 1986, but by 2019 had faded by a factor of nearly 400. It is located at the center of a galaxy (SDSS J153350.89+272729) at 147 Mpc, which shows weak Type II Seyfert activity. We show that a tidal disruption event (TDE) is the preferred scenario for FIRST J153350.8+272729, although it could plausibly be interpreted as the afterglow of a long-duration γ -ray burst. This is only the second TDE candidate to be first discovered at radio wavelengths. Its luminosity fills a gap between the radio afterglows of subrelativistic TDEs in the local universe, and relativistic TDEs at high redshifts. The unusual properties of FIRST J153350.8+272729 (ongoing nuclear activity in the host galaxy, high radio luminosity) motivate more extensive TDE searches in untargeted radio surveys.
The Australia Telescope Compact Array H I Survey of the Galactic Center
Publisher: American Astronomical Society
Date: 29-02-2012
Polarization Pipeline for Fast Radio Bursts Detected by CHIME/FRB
Publisher: American Astronomical Society
Date: 10-2021
Discovery of ASKAP J173608.2–321635 as a Highly Polarized Transient Point Source with the Australian SKA Pathfinder
Publisher: American Astronomical Society
Date: 10-2021
Hunting for Radio Emission from the Intermittent Pulsar J1107-5907 at Low Frequencies
Publisher: American Astronomical Society
Date: 19-12-2018
Observations and modelling of pulsed radio emission from CU Virginis
Publisher: Oxford University Press (OUP)
Date: 05-03-2012
Untwisting the Tornado: X-Ray Imaging and Spectroscopy of G357.7-0.1
Publisher: American Astronomical Society
Date: 08-08-2003
DOI: 10.1086/378260
Erratum: Science with the murchison widefield array: Phase I results and phase II opportunities (Publications of the Astronomical Society of Australia (2019) 36 (1-30) DOI: 10.1017/pasa.2019.41)
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.4
Low-frequency radio constraints on the synchrotron cosmic web
Publisher: Oxford University Press (OUP)
Date: 20-02-2017
DOI: 10.1093/MNRAS/STX424
The Southern Galactic Plane Survey: H I Observations and Analysis
Publisher: American Astronomical Society
Date: 06-2005
DOI: 10.1086/430114
An FRB Sent Me a DM: Constraining the Electron Column of the Milky Way Halo with Fast Radio Burst Dispersion Measures from CHIME/FRB
Publisher: American Astronomical Society
Date: 30-03-2023
Abstract: The CHIME/FRB project has detected hundreds of fast radio bursts (FRBs), providing an unparalleled population to statistically probe the foreground media that they illuminate. One such foreground medium is the ionized halo of the Milky Way (MW). We estimate the total Galactic electron column density from FRB dispersion measures (DMs) as a function of Galactic latitude using four different estimators, including ones that assume spherical symmetry of the ionized MW halo and ones that imply more latitudinal variation in density. Our observation-based constraints of the total Galactic DM contribution for ∣ b ∣ ≥ 30°, depending on the Galactic latitude and selected model, span 87.8–141 pc cm −3 . This constraint implies upper limits on the MW halo DM contribution that range over 52–111 pc cm −3 . We discuss the viability of various gas density profiles for the MW halo that have been used to estimate the halo’s contribution to DMs of extragalactic sources. Several models overestimate the DM contribution, especially when assuming higher halo gas masses (∼3.5 × 10 12 M ⊙ ). Some halo models predict a higher MW halo DM contribution than can be supported by our observations unless the effect of feedback is increased within them, highlighting the impact of feedback processes in galaxy formation.
Chandra Detection of a Synchrotron Nebula around the Vela-like Pulsar J1016-5857
Publisher: American Astronomical Society
Date: 12-2004
DOI: 10.1086/424924
Enhanced Small-Scale Faraday Rotation in the Galactic Spiral Arms
Publisher: American Astronomical Society
Date: 17-01-2006
DOI: 10.1086/500543
Absolutely calibrated radio polarimetry of the inner Galaxy at 2.3 and 4.8 GHz
Publisher: Oxford University Press (OUP)
Date: 03-12-2013
The Murchison Widefield Array Transients Survey (MWATS). A search for low frequency variability in a bright Southern hemisphere sample
Publisher: Oxford University Press (OUP)
Date: 18-10-2018
G309.2-00.6 and jets in supernova remnants
Publisher: Oxford University Press (OUP)
Date: 09-1998
ANXMM-NEWTONSTUDY OF THE BRIGHT, NEARBY SUPERNOVA REMNANT G296.1-0.5
Publisher: American Astronomical Society
Date: 27-05-2011
Are supershells powered by multiple supernovae? Modeling the radio pulsar population produced by OB associations
Publisher: American Astronomical Society
Date: 05-2004
DOI: 10.1086/382868
Parametrizing Epoch of Reionization foregrounds: a deep survey of low-frequency point-source spectra with the Murchison Widefield Array
Publisher: Oxford University Press (OUP)
Date: 11-02-2016
DOI: 10.1093/MNRAS/STW310
Linked Evolution of Gas and Star Formation in Galaxies Over Cosmic History
Publisher: American Astronomical Society
Date: 27-06-2008
DOI: 10.1086/590494
The interstellar matter in the direction of the supernova remnant G296.5+10.0 and the central X-ray source 1E 1207.4-5209
Publisher: American Astronomical Society
Date: 2000
DOI: 10.1086/301173
The Southern Galactic Plane Survey: The Test Region
Publisher: American Astronomical Society
Date: 10-04-2001
DOI: 10.1086/320095
Chandra observations of the high-magnetic-field radio pulsar J1718-3718
Publisher: AIP
Date: 2011
DOI: 10.1063/1.3629487
CHIME/FRB Discovery of 25 Repeating Fast Radio Burst Sources
Publisher: American Astronomical Society
Date: 04-2023
Abstract: We present the discovery of 25 new repeating fast radio burst (FRB) sources found among CHIME/FRB events detected between 2019 September 30 and 2021 May 1. The sources were found using a new clustering algorithm that looks for multiple events colocated on the sky having similar dispersion measures (DMs). The new repeaters have DMs ranging from ∼220 to ∼1700 pc cm −3 , and include sources having exhibited as few as two bursts to as many as twelve. We report a statistically significant difference in both the DM and extragalactic DM (eDM) distributions between repeating and apparently nonrepeating sources, with repeaters having a lower mean DM and eDM, and we discuss the implications. We find no clear bimodality between the repetition rates of repeaters and upper limits on repetition from apparently nonrepeating sources after correcting for sensitivity and exposure effects, although some active repeating sources stand out as anomalous. We measure the repeater fraction over time and find that it tends to an equilibrium of 2.6 − 2.6 + 2.9 % over our total time-on-sky thus far. We also report on 14 more sources, which are promising repeating FRB candidates and which merit follow-up observations for confirmation.
The Peculiar X-Ray Transient IGR J16358-4726
Publisher: American Astronomical Society
Date: 02-02-2004
DOI: 10.1086/382210
Chandra Observations of the Crab-like Supernova Remnant G21.5-0.9
Publisher: American Astronomical Society
Date: 10-04-2000
DOI: 10.1086/312589
Abstract: Chandra observations of the Crab-like supernova remnant G21.5-0.9 reveal a compact central core and spectral variations indicative of synchrotron burn-off of higher energy electrons in the inner nebula. The central core is slightly extended, perhaps indicating the presence of an inner wind-shock nebula surrounding the pulsar. No pulsations are observed from the central region, yielding an upper limit of approximately 40% for the pulsed fraction. A faint outer shell may be the first evidence of the expanding ejecta and blast wave formed in the initial explosion, indicating a composite nature for G21.5-0.9.
A 20-yr radio light curve for the young supernova remnant G1.9+0.3
Publisher: Oxford University Press (OUP)
Date: 09-2008
The Structure of Galactic Hydrogen on the Largest Scales
Publisher: Kluwer Academic Publishers
Date: 2004
Diagnosing the Outflow from the SGR 1806−20 Giant Flare with Radio Observations
Publisher: American Astronomical Society
Date: 10-02-2006
DOI: 10.1086/497680
High resolution polarimetry of the inner galaxy
Publisher: AIP
Date: 2002
DOI: 10.1063/1.1471818
The case for associations between old pulsars and supernova remnants
Publisher: Oxford University Press (OUP)
Date: 07-1995
Angular spectra of Galactic polarized synchrotron emission at Arcmin scales
Publisher: AIP
Date: 2002
DOI: 10.1063/1.1471824
Radio polarization properties of quasars and active galaxies at high redshifts
Publisher: Oxford University Press (OUP)
Date: 11-12-2018
A Rebrightening of the Radio Nebula Associated with the 2004 December 27 Giant Flare from SGR 1806-20
Publisher: American Astronomical Society
Date: 08-11-2005
DOI: 10.1086/498643
FARADAY ROTATION MEASURE SYNTHESIS OF INTERMEDIATE REDSHIFT QUASARS AS A PROBE OF INTERVENING MATTER
Publisher: American Astronomical Society
Date: 29-09-2016
A new perspective on turbulent Galactic magnetic fields through comparison of linear polarization decomposition techniques
Publisher: Oxford University Press (OUP)
Date: 15-03-2017
DOI: 10.1093/MNRAS/STX642
DELAY SPECTRUM WITH PHASE-TRACKING ARRAYS: EXTRACTING THE H i POWER SPECTRUM FROM THE EPOCH OF REIONIZATION
Publisher: American Astronomical Society
Date: 19-12-2016
Magnetic Fields in Large-diameter H II Regions Revealed by the Faraday Rotation of Compact Extragalactic Radio Sources
Publisher: American Astronomical Society
Date: 11-07-2011
A CHIME/FRB Study of Burst Rate and Morphological Evolution of the Periodically Repeating FRB 20180916B
Publisher: American Astronomical Society
Date: 10-2023
The mouse that soared: High-resolution X-ray imaging of the pulsar-powered bow shock G359.23-0.82
Publisher: American Astronomical Society
Date: 20-11-2004
DOI: 10.1086/424906
Detection of microgauss coherent magnetic fields in a galaxy five billion years ago
Publisher: Springer Science and Business Media LLC
Date: 28-08-2017
Discovery of Pulsations and a Possible Spectral Feature in the X‐Ray Emission from Rotating Radio Transient J1819−1458
Publisher: American Astronomical Society
Date: 12-2007
DOI: 10.1086/522335
Remnant radio galaxies discovered in a multi-frequency survey
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2020.49
Abstract: The remnant phase of a radio galaxy begins when the jets launched from an active galactic nucleus are switched off. To study the fraction of radio galaxies in a remnant phase, we take advantage of a $8.31$ deg $^2$ subregion of the GAMA 23 field which comprises of surveys covering the frequency range 0.1–9 GHz. We present a s le of 104 radio galaxies compiled from observations conducted by the Murchison Widefield Array (216 MHz), the Australia Square Kilometer Array Pathfinder (887 MHz), and the Australia Telescope Compact Array (5.5 GHz). We adopt an ‘absent radio core’ criterion to identify 10 radio galaxies showing no evidence for an active nucleus. We classify these as new candidate remnant radio galaxies. Seven of these objects still display compact emitting regions within the lobes at 5.5 GHz at this frequency the emission is short-lived, implying a recent jet switch off. On the other hand, only three show evidence of aged lobe plasma by the presence of an ultra-steep-spectrum ( $\\alpha -1.2$ ) and a diffuse, low surface brightness radio morphology. The predominant fraction of young remnants is consistent with a rapid fading during the remnant phase. Within our s le of radio galaxies, our observations constrain the remnant fraction to $4\\%\\lesssim f_{\\mathrm{rem}} \\lesssim 10\\%$ the lower limit comes from the limiting case in which all remnant candidates with hotspots are simply active radio galaxies with faint, undetected radio cores. Finally, we model the synchrotron spectrum arising from a hotspot to show they can persist for 5–10 Myr at 5.5 GHz after the jets switch of—radio emission arising from such hotspots can therefore be expected in an appreciable fraction of genuine remnants.
Classifying Complex Faraday Spectra with Convolutional Neural Networks
Publisher: Oxford University Press (OUP)
Date: 27-10-2018
Transient radio emission from sax j1808.423658
Publisher: American Astronomical Society
Date: 10-09-1999
DOI: 10.1086/312238
The Galactic Magneto-ionic Medium Survey: Moments of the Faraday Spectra
Publisher: American Astronomical Society
Date: 25-01-2019
Thermal plasma in the giant lobes of the radio galaxy Centaurus A
Publisher: American Astronomical Society
Date: 04-02-2013
Multi-wavelength radio monitoring of EGRET sources and candidates
Publisher: AIP
Date: 1997
DOI: 10.1063/1.53956
A New Supernova Remnant Coincident with the Slow X-Ray Pulsar AX J1845-0258
Publisher: American Astronomical Society
Date: 20-11-1999
DOI: 10.1086/312362
Abstract: We report on Very Large Array observations in the direction of the recently discovered slow X-ray pulsar AX J1845-0258. In the resulting images, we find a 5&arcmin shell of radio emission the shell is linearly polarized with a nonthermal spectral index. We classify this source as a previously unidentified, young (<8000 yr) supernova remnant (SNR), G29.6+0.1, which we propose is physically associated with AX J1845-0258. The young age of G29.6+0.1 is then consistent with the interpretation that anomalous X-ray pulsars (AXPs) are isolated, highly magnetized neutron stars ("magnetars"). Three of the six known AXPs can now be associated with SNRs we conclude that AXPs are young ( less, similar10,000 yr) objects and that they are produced in at least 5% of core-collapse supernovae.
Erratum: “The First CHIME/FRB Fast Radio Burst Catalog” (2021, ApJS, 257, 59)
Publisher: American Astronomical Society
Date: 02-2023
X-ray observations of the compact source in CTA 1
Publisher: American Astronomical Society
Date: 02-2004
DOI: 10.1086/380498
Low-Mach-number turbulence in interstellar gas revealed by radio polarization gradients
Publisher: Springer Science and Business Media LLC
Date: 10-2011
DOI: 10.1038/NATURE10446
Abstract: The interstellar medium of the Milky Way is multiphase, magnetized and turbulent. Turbulence in the interstellar medium produces a global cascade of random gas motions, spanning scales ranging from 100 parsecs to 1,000 kilometres (ref. 4). Fundamental parameters of interstellar turbulence such as the sonic Mach number (the speed of sound) have been difficult to determine, because observations have lacked the sensitivity and resolution to image the small-scale structure associated with turbulent motion. Observations of linear polarization and Faraday rotation in radio emission from the Milky Way have identified unusual polarized structures that often have no counterparts in the total radiation intensity or at other wavelengths, and whose physical significance has been unclear. Here we report that the gradient of the Stokes vector (Q, U), where Q and U are parameters describing the polarization state of radiation, provides an image of magnetized turbulence in diffuse, ionized gas, manifested as a complex filamentary web of discontinuities in gas density and magnetic field. Through comparison with simulations, we demonstrate that turbulence in the warm, ionized medium has a relatively low sonic Mach number, M(s) ≲ 2. The development of statistical tools for the analysis of polarization gradients will allow accurate determinations of the Mach number, Reynolds number and magnetic field strength in interstellar turbulence over a wide range of conditions.
Searching for Compact Objects in Supernova Remnants:. Initial Results
Publisher: WORLD SCIENTIFIC
Date: 08-2004
A new pulsar/SNR pair: AX J1845-0258 in G29.6+0.1
Publisher: AIP
Date: 2001
DOI: 10.1063/1.1434658
A Half-Megasecond Chandra Observation of the Oxygen-rich Supernova Remnant G292.0+1.8
Publisher: American Astronomical Society
Date: 31-10-2007
DOI: 10.1086/524406
Removing non-physical structure in fitted Faraday rotated signals: Non-parametric QU-fitting
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.49
Abstract: Next-generation spectro-polarimetric broadband surveys will probe cosmic magnetic fields in unprecedented detail, using the magneto-optical effect known as Faraday rotation. However, non-parametric methods such as RMCLEAN can introduce non-observable linearly polarised flux into a fitted model at negative wavelengths squared. This leads to Faraday rotation structures that are consistent with the observed data, but would be impossible or difficult to measure. We construct a convex non-parametric QU -fitting algorithm to constrain the flux at negative wavelengths squared to be zero. This allows the algorithm to recover structures that are limited in complexity to the observable region in wavelength squared. We verify this approach on simulated broadband data sets where we show that it has a lower root mean square error and that it can change the scientific conclusions for real observations. We advise using this prior in next-generation broadband surveys that aim to uncover complex Faraday depth structures. We provide a public Python implementation of the algorithm at github.com/Luke-Pratley/Faraday-Dreams .
GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) I: Survey description and initial data release
Publisher: Cambridge University Press (CUP)
Date: 2022
DOI: 10.1017/PASA.2022.17
Abstract: We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72–231 MHz and Declinations south of $+30^\\circ$ have been performed with the Murchison Widefield Array “extended” Phase II configuration over 2018–2020 and will be processed to form data products including continuum and polarisation images and mosaics, multi-frequency catalogues, transient search data, and ionospheric measurements. From a pilot field described in this work, we publish an initial data release covering 1,447 $\\mathrm{deg}^2$ over $4\\,\\mathrm{h}\\leq \\mathrm{RA}\\leq 13\\,\\mathrm{h}$ , $-32.7^\\circ \\leq \\mathrm{Dec} \\leq -20.7^\\circ$ . We process twenty frequency bands s ling 72–231 MHz, with a resolution of 2′–45 ′′ , and produce a wideband source-finding image across 170–231 MHz with a root mean square noise of $1.27\\pm0.15\\,\\mathrm{mJy\\,beam}^{-1}$ . Source-finding yields 78,967 components, of which 71,320 are fitted spectrally. The catalogue has a completeness of 98% at ${{\\sim}}50\\,\\mathrm{mJy}$ , and a reliability of 98.2% at $5\\sigma$ rising to 99.7% at $7\\sigma$ . A catalogue is available from Vizier images are made available via the PASA datastore, AAO Data Central, and SkyView. This is the first in a series of data releases from the GLEAM-X survey.
The Dispersion and Rotation Measure of Supernova Remnants and Magnetized Stellar Winds: Application to Fast Radio Bursts
Publisher: American Astronomical Society
Date: 16-07-2018
Analytic detection thresholds for measurements of linearly polarized intensity using rotation measure synthesis
Publisher: Oxford University Press (OUP)
Date: 03-07-2012
Improving the Epoch of Reionization Power Spectrum Results from Murchison Widefield Array Season 1 Observations
Publisher: American Astronomical Society
Date: 07-10-2019
The Square Kilometre Array (SKA)
Publisher: Cambridge University Press (CUP)
Date: 08-2007
DOI: 10.1017/S1743921307011143
Abstract: The Square Kilometre Array SKA is intended to be the centimeter- and meter-wavelength telescope for the 21 st century. At long wavelengths, the SKA's key science projects include the search for highly redshifted hydrogen, including the signal from the epoch of re-ionization, and the search for the first supermassive black holes.
Structure in the radio counterpart to the 2004 December 27 giant flare from SGR 1806-20
Publisher: Oxford University Press (OUP)
Date: 03-2006
The X-ray emission of the highly magnetic RRAT J1819–1458
Publisher: AIP
Date: 2008
DOI: 10.1063/1.2900323
SPECTROPOLARIMETRY WITH THE ALLEN TELESCOPE ARRAY: FARADAY ROTATION TOWARD BRIGHT POLARIZED RADIO GALAXIES
Publisher: American Astronomical Society
Date: 20-01-2011
S-band Polarization All-Sky Survey (S-PASS): survey description and maps
Publisher: Oxford University Press (OUP)
Date: 05-09-2019
DOI: 10.1093/MNRAS/STZ806
Abstract: We present the S-Band Polarization All Sky Survey (S-PASS), a survey of polarized radio emission over the southern sky at Dec. & −1° taken with the Parkes radio telescope at 2.3 GHz. The main aim was to observe at a frequency high enough to avoid strong depolarization at intermediate Galactic latitudes (still present at 1.4 GHz) to study Galactic magnetism, but low enough to retain le signal-to-noise ratio (S/N) at high latitudes for extragalactic and cosmological science. We developed a new scanning strategy based on long azimuth scans and a corresponding map-making procedure to make recovery of the overall mean signal of Stokes Q and U possible, a long-standing problem with polarization observations. We describe the scanning strategy, map-making procedure and validation tests. The overall mean signal is recovered with a precision better than 0.5 per cent. The maps have a mean sensitivity of 0.81 mK on beam-size scales and show clear polarized signals, typically to within a few degrees of the Galactic plane, with le S/N everywhere (the typical signal in low-emission regions is 13 mK and 98.6 per cent of pixels have S/N & 3). The largest depolarization areas are in the inner Galaxy, associated with the Sagittarius Arm. We have also computed a rotation measure map combining S-PASS with archival data from the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck experiments. A Stokes I map has been generated, with sensitivity limited to the confusion level of 9 mK.
Limiting magnetic fields in the cosmic web with diffuse radio emission
Publisher: Oxford University Press (OUP)
Date: 25-03-2017
DOI: 10.1093/MNRAS/STX746
X-Ray Observations of the Compact Central Object in Supernova Remnant G347.3-0.5
Publisher: American Astronomical Society
Date: 15-07-2003
DOI: 10.1086/378183
Revealing the Dynamic Magnetoionic Environments of Repeating Fast Radio Burst Sources through Multiyear Polarimetric Monitoring with CHIME/FRB
Publisher: American Astronomical Society
Date: 07-2023
Abstract: Fast radio bursts (FRBs) display a confounding variety of burst properties and host-galaxy associations. Repeating FRBs offer insight into the FRB population by enabling spectral, temporal, and polarimetric properties to be tracked over time. Here, we report on the polarized observations of 12 repeating sources using multiyear monitoring with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) over 400–800 MHz. We observe significant rotation measure (RM) variations from many sources in our s le, including RM changes of several hundred radians per square meter over month timescales from FRBs 20181119A, 20190303A, and 20190417A, and more modest RM variability (ΔRM ≲ few tens of radians per square meter) from FRBs 20181030A, 20190208A, 20190213B, and 20190117A over equivalent timescales. Several repeaters display a frequency-dependent degree of linear polarization that is consistent with depolarization via scattering. Combining our measurements of RM variations with equivalent constraints on DM variability, we estimate the average line-of-sight magnetic field strength in the local environment of each repeater. In general, repeating FRBs display RM variations that are more prevalent and/or extreme than those seen from radio pulsars in the Milky Way and the Magellanic Clouds, suggesting repeating FRBs and pulsars occupy distinct magnetoionic environments.
Detection of Linear Polarization in the Radio Remnant of Supernova 1987A
Publisher: American Astronomical Society
Date: 29-06-2018
A Radio Continuum and Polarization Study of SNR G57.2+0.8 Associated with Magnetar SGR 1935+2154
Publisher: American Astronomical Society
Date: 05-01-2018
SPATIAL, TEMPORAL, AND SPECTRAL PROPERTIES OF X-RAY EMISSION FROM THE MAGNETAR SGR 0501+4516
Publisher: American Astronomical Society
Date: 23-09-2010
Discovery of the X-Ray Counterpart to the Rotating Radio Transient J1819-1458
Publisher: American Astronomical Society
Date: 13-02-2006
DOI: 10.1086/502648
Constraining the Magnetic Field of the Smith High-velocity Cloud Using Faraday Rotation
Publisher: American Astronomical Society
Date: 02-2019
The GLEAM 200-MHz local radio luminosity function for AGN and star-forming galaxies
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.36
Abstract: The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) is a radio continuum survey at 76–227 MHz of the entire southern sky (Declination $ \\!{+}30^{\\circ}$ ) with an angular resolution of ${\\approx}2$ arcmin. In this paper, we combine GLEAM data with optical spectroscopy from the 6dF Galaxy Survey to construct a s le of 1 590 local (median $z \\approx 0.064$ ) radio sources with $S_{200\\,\\mathrm{MHz}} 55$ mJy across an area of ${\\approx}16\\,700\\,\\mathrm{deg}^{2}$ . From the optical spectra, we identify the dominant physical process responsible for the radio emission from each galaxy: 73% are fuelled by an active galactic nucleus (AGN) and 27% by star formation. We present the local radio luminosity function for AGN and star-forming (SF) galaxies at 200 MHz and characterise the typical radio spectra of these two populations between 76 MHz and ${\\sim}1$ GHz. For the AGN, the median spectral index between 200 MHz and ${\\sim}1$ GHz, $\\alpha_{\\mathrm{high}}$ , is $-0.600 \\pm 0.010$ (where $S \\propto \\nu^{\\alpha}$ ) and the median spectral index within the GLEAM band, $\\alpha_{\\mathrm{low}}$ , is $-0.704 \\pm 0.011$ . For the SF galaxies, the median value of $\\alpha_{\\mathrm{high}}$ is $-0.650 \\pm 0.010$ and the median value of $\\alpha_{\\mathrm{low}}$ is $-0.596 \\pm 0.015$ . Among the AGN population, flat-spectrum sources are more common at lower radio luminosity, suggesting the existence of a significant population of weak radio AGN that remain core-dominated even at low frequencies. However, around 4% of local radio AGN have ultra-steep radio spectra at low frequencies ( $\\alpha_{\\mathrm{low}} -1.2$ ). These ultra-steep-spectrum sources span a wide range in radio luminosity, and further work is needed to clarify their nature.
THE MAGNETIC FIELD and POLARIZATION PROPERTIES of RADIO GALAXIES in DIFFERENT ACCRETION STATES
Publisher: American Astronomical Society
Date: 09-06-2015
FARADAY ROTATION STRUCTURE ON KILOPARSEC SCALES IN THE RADIO LOBES OF CENTAURUS A
Publisher: American Astronomical Society
Date: 18-11-2009
RADIO POLARIZATION OBSERVATIONS OF G319.9–0.7: A BOW-SHOCK NEBULA WITH AN AZIMUTHAL MAGNETIC FIELD POWERED BY PULSAR J1509–5850
Publisher: American Astronomical Society
Date: 04-03-2010
FARADAY TOMOGRAPHY OF THE NORTH POLAR SPUR: CONSTRAINTS ON THE DISTANCE TO THE SPUR AND ON THE MAGNETIC FIELD OF THE GALAXY
Publisher: American Astronomical Society
Date: 16-09-2015
High-resolution X-ray Observations of the Pulsar Wind Nebula Associated with the Gamma-ray Source HESS J1640-465
Publisher: American Astronomical Society
Date: 11-11-2009
The x-ray transient 2XMMi J003833.3+402133: A candidate magnetar at high galactic latitude
Publisher: American Astronomical Society
Date: 14-09-2012
A Chandra Observation of Supernova Remnant G350.1-0.3 and Its Central Compact Object
Publisher: American Astronomical Society
Date: 24-03-2011
Another shock for the Bullet cluster, and the source of seed electrons for radio relics
Publisher: Oxford University Press (OUP)
Date: 24-03-2015
DOI: 10.1093/MNRAS/STV334
An X-Ray Search for Compact Central Sources in Supernova Remnants. II. Six Large-Diameter SNRs
Publisher: American Astronomical Society
Date: 04-2006
DOI: 10.1086/501441
The ASKAP Variables and Slow Transients (VAST) Pilot Survey
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.44
Abstract: The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable and transient radio sources on timescales from 5 s to $\\sim\\!5$ yr. In this paper, we present the survey description, observation strategy and initial results from the VAST Phase I Pilot Survey. This pilot survey consists of $\\sim\\!162$ h of observations conducted at a central frequency of 888 MHz between 2019 August and 2020 August, with a typical rms sensitivity of $0.24\\ \\mathrm{mJy\\ beam}^{-1}$ and angular resolution of $12-20$ arcseconds. There are 113 fields, each of which was observed for 12 min integration time, with between 5 and 13 repeats, with cadences between 1 day and 8 months. The total area of the pilot survey footprint is 5 131 square degrees, covering six distinct regions of the sky. An initial search of two of these regions, totalling 1 646 square degrees, revealed 28 highly variable and/or transient sources. Seven of these are known pulsars, including the millisecond pulsar J2039–5617. Another seven are stars, four of which have no previously reported radio detection (SCR J0533–4257, LEHPM 2-783, UCAC3 89–412162 and 2MASS J22414436–6119311). Of the remaining 14 sources, two are active galactic nuclei, six are associated with galaxies and the other six have no multi-wavelength counterparts and are yet to be identified.
A radio polarization study of magnetic fields in the Small Magellanic Cloud
Publisher: Oxford University Press (OUP)
Date: 25-11-2021
Abstract: Observing the magnetic fields of low-mass interacting galaxies tells us how they have evolved over cosmic time and their importance in galaxy evolution. We have measured the Faraday rotation of 80 extra-galactic radio sources behind the Small Magellanic Cloud (SMC) using the CSIRO Australia Telescope Compact Array (ATCA) with a frequency range of 1.4–3.0 GHz. Both the sensitivity of our observations and the source density are an order-of-magnitude improvement on previous Faraday rotation measurements of this galaxy. The SMC generally produces negative rotation measures after accounting for the Milky Way foreground contribution, indicating that it has a mean coherent line-of-sight magnetic field strength of $-0.3\\pm 0.1\\, \\mu$G, consistent with previous findings. We detect signatures of magnetic fields extending from the north and south of the Bar of the SMC. The random component of the SMC magnetic field has a strength of $\\sim 5\\, \\mu$G with a characteristic size-scale of magneto-ionic turbulence & pc, making the SMC like other low-mass interacting galaxies. The magnetic fields of the SMC and Magellanic Bridge appear similar in direction and strength, hinting at a connection between the two fields as part of the hypothesized ‘pan-Magellanic’ magnetic field.
Related Organisations
Massachusetts Institute Of Technology
Location: United States of America
University Of California Santa Cruz
Location: United States of America
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