ORCID Profile
0000-0003-1731-0497
Current Organisation
Australian National University
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Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy | Astronomical and Space Instrumentation | Astronomical sciences | Astronomical instrumentation | Space instrumentation | Astronomy And Astrophysics | Astronomical sciences not elsewhere classified | Cosmology and extragalactic astronomy | Lasers and quantum electronics | Galactic Astronomy | General relativity and gravitational waves
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Engineering | Physical sciences | Expanding Knowledge in Technology |
Publisher: IOP Publishing
Date: 09-2021
Publisher: EDP Sciences
Date: 02-2012
Publisher: EDP Sciences
Date: 08-2013
Publisher: American Astronomical Society
Date: 08-02-2018
Publisher: Oxford University Press (OUP)
Date: 21-11-2022
Abstract: This paper presents a new optical imaging survey of four deep drilling fields (DDFs), two Galactic and two extragalactic, with the Dark Energy Camera (DECam) on the 4-m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO). During the first year of observations in 2021, & images covering 21 deg2 (seven DECam pointings), with ∼40 epochs (nights) per field and 5 to 6 images per night per filter in g, r, i, and/or z have become publicly available (the proprietary period for this program is waived). We describe the real-time difference-image pipeline and how alerts are distributed to brokers via the same distribution system as the Zwicky Transient Facility (ZTF). In this paper, we focus on the two extragalactic deep fields (COSMOS and ELAIS-S1) characterizing the detected sources, and demonstrating that the survey design is effective for probing the discovery space of faint and fast variable and transient sources. We describe and make publicly available 4413 calibrated light curves based on difference-image detection photometry of transients and variables in the extragalactic fields. We also present preliminary scientific analysis regarding the Solar system small bodies, stellar flares and variables, Galactic anomaly detection, fast-rising transients and variables, supernovae, and active Galactic nuclei.
Publisher: Oxford University Press (OUP)
Date: 19-02-2019
DOI: 10.1093/MNRAS/STZ463
Publisher: Cambridge University Press (CUP)
Date: 10-2005
Publisher: Springer Berlin Heidelberg
Date: 2008
Publisher: American Astronomical Society
Date: 06-04-2012
Publisher: American Astronomical Society
Date: 17-05-2021
Abstract: We describe the Dark Energy Survey (DES) photometric data set assembled from the first three years of science operations to support DES Year 3 cosmologic analyses, and provide usage notes aimed at the broad astrophysics community. Y3 GOLD improves on previous releases from DES, Y1 GOLD , and Data Release 1 (DES DR1), presenting an expanded and curated data set that incorporates algorithmic developments in image detrending and processing, photometric calibration, and object classification. Y3 GOLD comprises nearly 5000 deg 2 of grizY imaging in the south Galactic cap, including nearly 390 million objects, with depth reaching a signal-to-noise ratio ∼10 for extended objects up to i AB ∼ 23.0, and top-of-the-atmosphere photometric uniformity mmag. Compared to DR1, photometric residuals with respect to Gaia are reduced by 50%, and per-object chromatic corrections are introduced. Y3 GOLD augments DES DR1 with simultaneous fits to multi-epoch photometry for more robust galactic color measurements and corresponding photometric redshift estimates. Y3 GOLD features improved morphological star–galaxy classification with efficiency % and purity % for galaxies with 19 i AB 22.5. Additionally, it includes per-object quality information, and accompanying maps of the footprint coverage, masked regions, imaging depth, survey conditions, and astrophysical foregrounds that are used to select the cosmologic analysis s les.
Publisher: Oxford University Press (OUP)
Date: 20-12-2013
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.24
Abstract: SN1991bg-like supernovae are a distinct subclass of thermonuclear Type Ia supernovae (SNe Ia). Their spectral and photometric peculiarities indicate that their progenitors and explosion mechanisms differ from ‘normal’ SNe Ia. One method of determining information about supernova progenitors we cannot directly observe is to observe the stellar population adjacent to the apparent supernova explosion site to infer the distribution of stellar population ages and metallicities. We obtain integral field observations and analyse the spectra extracted from regions of projected radius $\\sim\\,\\text{kpc}$ about the apparent SN explosion site for 11 91bg-like SNe in both early- and late-type galaxies. We utilise full-spectrum spectral fitting to determine the ages and metallicities of the stellar population within the aperture. We find that the majority of the stellar populations that hosted 91bg-like supernovae have little recent star formation. The ages of the stellar populations suggest that that 91bg-like SN progenitors explode after delay times of Gyr, much longer than the typical delay time of normal SNe Ia, which peaks at $\\sim$ 1 Gyr.
Publisher: American Astronomical Society
Date: 21-08-2015
Publisher: Oxford University Press (OUP)
Date: 17-05-2019
Abstract: The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 μm) with the UKIRT and the AAT, and in the NB2090 band (2.1 μm) with the VLT during the period 2015–18. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of 0.003 (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of 3 yr. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.
Publisher: Springer-Verlag
DOI: 10.1007/10857580_58
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B606395K
Publisher: American Astronomical Society
Date: 16-10-2015
Publisher: Oxford University Press (OUP)
Date: 03-04-2020
Abstract: We study the properties of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz radio active galactic nuclei (AGNs) population in galaxy clusters from two large catalogues created using the Dark Energy Survey (DES): ∼11 800 optically selected RM-Y3 and ∼1000 X-ray selected MARD-Y3 clusters. We show that cluster radio loud AGNs are highly concentrated around cluster centres to $z$ ∼ 1. We measure the halo occupation number for cluster radio AGNs above a threshold luminosity, finding that the number of radio AGNs per cluster increases with cluster halo mass as N ∝ M1.2 ± 0.1 (N ∝ M0.68 ± 0.34) for the RM-Y3 (MARD-Y3) s le. Together, these results indicate that radio mode feedback is favoured in more massive galaxy clusters. Using optical counterparts for these sources, we demonstrate weak redshift evolution in the host broad-band colours and the radio luminosity at fixed host galaxy stellar mass. We use the redshift evolution in radio luminosity to break the degeneracy between density and luminosity evolution scenarios in the redshift trend of the radio AGNs luminosity function (LF). The LF exhibits a redshift trend of the form (1 + $z$)γ in density and luminosity, respectively, of γD = 3.0 ± 0.4 and γP = 0.21 ± 0.15 in the RM-Y3 s le, and γD = 2.6 ± 0.7 and γP = 0.31 ± 0.15 in MARD-Y3. We discuss the physical drivers of radio mode feedback in cluster AGNs, and we use the cluster radio galaxy LF to estimate the average radio-mode feedback energy as a function of cluster mass and redshift and compare it to the core (& .1R500) X-ray radiative losses for clusters at $z$ & 1.
Publisher: American Astronomical Society
Date: 10-08-2002
DOI: 10.1086/341261
Publisher: American Astronomical Society
Date: 08-01-2019
Publisher: EDP Sciences
Date: 19-06-2013
Publisher: American Astronomical Society
Date: 08-2019
Publisher: American Astronomical Society
Date: 03-11-2020
Publisher: American Astronomical Society
Date: 03-01-2013
Publisher: EDP Sciences
Date: 08-04-2009
Publisher: EDP Sciences
Date: 24-04-2007
Publisher: EDP Sciences
Date: 02-2005
Publisher: National Library of Serbia
Date: 2021
Abstract: Introduction/Objective. Essential Science Indicators (ESI) Highly Cited Papers (HCPs) refer to the most influential scientific articles and breakthrough research within a research field in the past decade. This study aimed to identify the characteristics of ESI HCPs in the subject category Dentistry, Oral Surgery and Medicine, to recognize authors, institutions and countries of origin, and determine research trends that attracted the most scientific interest in dentistry. Methods. A descriptive analysis of bibliographic data, network extraction and visualization were completed. Furthermore, analyzed ESI HCPs were classified according to a field of interest, main research domain, type of study, and level of evidence. Results. The set of 185 dental HCPs was published in 42 journals from 2010 to 2020, with an average number of 211.7 citations per paper. Nearly half of HCPs were issued by the Journal of Dental Research, Dental Materials, and Journal of Clinical Periodontology. There were 765 authors affiliated with 351 institutions from 42 countries. The most productive institutions were the University of Hong Kong, the University of Michigan, and the University of Bern. The United States of America contributed with the highest number of publications, followed by China, and the United Kingdom. Dental materials, dental implantology, periodontology, and oral and maxillofacial surgery represented areas of significant interest within this subject category. The highest proportion of HCPs were narrative and systematic reviews, expert opinions, consensus reports, and in vitro ?r lab studies. Conclusion. Results obtained from this study can provide valuable information for researchers to better identify present and future hotspots in dental research.
Publisher: Oxford University Press (OUP)
Date: 24-03-2017
DOI: 10.1093/MNRAS/STX722
Publisher: American Astronomical Society
Date: 20-11-2003
DOI: 10.1086/378560
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B701504F
Publisher: American Astronomical Society
Date: 09-11-2017
Publisher: SPIE
Date: 30-09-2004
DOI: 10.1117/12.552048
Publisher: Oxford University Press (OUP)
Date: 13-08-2022
Abstract: We present a s le of 706, z & 1.5 active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg2. We construct light curves using difference imaging aperture photometry for resolved sources and non-difference imaging PSF photometry for unresolved sources, respectively, and characterize the variability significance. Our DES light curves have a mean cadence of 7 d, a 6-yr baseline, and a single-epoch imaging depth of up to g ∼ 24.5. Using spectral energy distribution (SED) fitting, we find 26 out of total 706 variable galaxies are consistent with dwarf galaxies with a reliable stellar mass estimate ($M_{\\ast }\\lt 10^{9.5}\\, {\\rm M}_\\odot$ median photometric redshift of 0.9). We were able to constrain rapid characteristic variability time-scales (∼ weeks) using the DES light curves in 15 dwarf AGN candidates (a subset of our variable AGN candidates) at a median photometric redshift of 0.4. This rapid variability is consistent with their low black hole (BH) masses. We confirm the low-mass AGN nature of one source with a high S/N optical spectrum. We publish our catalogue, optical light curves, and supplementary data, such as X-ray properties and optical spectra, when available. We measure a variable AGN fraction versus stellar mass and compare to results from a forward model. This work demonstrates the feasibility of optical variability to identify AGNs with lower BH masses in deep fields, which may be more ‘pristine’ analogues of supermassive BH seeds.
Publisher: American Astronomical Society
Date: 12-12-2008
Publisher: American Astronomical Society
Date: 08-1998
DOI: 10.1086/311509
Publisher: American Astronomical Society
Date: 06-1999
DOI: 10.1086/307221
Publisher: Springer Science and Business Media LLC
Date: 2005
DOI: 10.1038/NATURE03225
Abstract: Mass is the most fundamental parameter of a star, yet it is also one of the most difficult to measure directly. In general, astronomers estimate stellar masses by determining the luminosity and using the 'mass-luminosity' relationship, but this relationship has never been accurately calibrated for young, low-mass stars and brown dwarfs. Masses for these low-mass objects are therefore constrained only by theoretical models. A new high-contrast adaptive optics camera enabled the discovery of a young (50 million years) companion only 0.156 arcseconds (2.3 au) from the more luminous (> 120 times brighter) star AB Doradus A. Here we report a dynamical determination of the mass of the newly resolved low-mass companion AB Dor C, whose mass is 0.090 +/- 0.005 solar masses. Given its measured 1-2-micrometre luminosity, we have found that the standard mass-luminosity relations overestimate the near-infrared luminosity of such objects by about a factor of approximately 2.5 at young ages. The young, cool objects hitherto thought to be substellar in mass are therefore about twice as massive, which means that the frequency of brown dwarfs and planetary mass objects in young stellar clusters has been overestimated.
Publisher: Oxford University Press (OUP)
Date: 10-02-2016
DOI: 10.1093/MNRAS/STW080
Publisher: Oxford University Press (OUP)
Date: 30-05-3202
Abstract: We present a description of the Australian Dark Energy Survey (OzDES) and summarize the results from its 6 years of operations. Using the 2dF fibre positioner and AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope, OzDES has monitored 771 active galactic nuclei, classified hundreds of supernovae, and obtained redshifts for thousands of galaxies that hosted a transient within the 10 deep fields of the Dark Energy Survey. We also present the second OzDES data release, containing the redshifts of almost 30 000 sources, some as faint as rAB = 24 mag, and 375 000 in idual spectra. These data, in combination with the time-series photometry from the Dark Energy Survey, will be used to measure the expansion history of the Universe out to z ∼ 1.2 and the masses of hundreds of black holes out to z ∼ 4. OzDES is a template for future surveys that combine simultaneous monitoring of targets with wide-field imaging cameras and wide-field multi-object spectrographs.
Publisher: EDP Sciences
Date: 06-2018
DOI: 10.1051/0004-6361/201731552
Abstract: Aims. Strong lensing by massive galaxy clusters can provide magnification of the flux and even multiple images of the galaxies that lie behind them. This phenomenon facilitates observations of high-redshift supernovae (SNe) that would otherwise remain undetected. Type Ia supernovae (SNe Ia) detections are of particular interest because of their standard brightness, since they can be used to improve either cluster lensing models or cosmological parameter measurements. Methods. We present a ground-based, near-infrared search for lensed SNe behind the galaxy cluster Abell 370. Our survey was based on 15 epochs of J -band observations with the HAWK-I instrument on the Very Large Telescope (VLT). We use Hubble Space Telescope (HST) photometry to infer the global properties of the multiply-imaged galaxies. Using a recently published lensing model of Abell 370, we also present the predicted magnifications and time delays between the images. Results. In our survey, we did not discover any live SNe from the 13 lensed galaxies with 47 multiple images behind Abell 370. This is consistent with the expectation of 0.09 ± 0.02 SNe calculated based on the measured star formation rate. We compare the expectations of discovering strongly lensed SNe in our survey and that performed with HST during the Hubble Frontier Fields (HFF) programme. We also show the expectations of search c aigns that can be conducted with future facilities, such as the James Webb Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST). We show that the NIRCam instrument aboard the JWST will be sensitive to most SN multiple images in the strongly lensed galaxies and thus will be able to measure their time delays if observations are scheduled accordingly.
Publisher: EDP Sciences
Date: 10-2020
DOI: 10.1051/0004-6361/202038505
Abstract: The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure and the gravitational lensing of background light through this cosmic web. By comparing the litude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys, BOSS and 2dFLenS, to perform the most precise existing litude-ratio test. We measured the associated E G statistic with 15 − 20% errors in five Δ z = 0.1 tomographic redshift bins in the range 0.2 z 0.7 on projected scales up to 100 h −1 Mpc. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Ω m = 0.27 ± 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and we compare the performance of angular and projected galaxy-galaxy lensing statistics.
Publisher: Oxford University Press (OUP)
Date: 17-05-2019
Abstract: We present deep, multiwavelength radio observations of SpARCS104922.6 + 564032.5, a z = 1.71 galaxy cluster with a starbursting core. Observations were made with the Karl G. Jansky Very Large Array (JVLA) in three bands: 1–2 GHz, 4–8 GHz, and 8–12 GHz. We detect a radio source coincident with the brightest cluster galaxy (BCG) that has a spectral index of α = 0.44 ± 0.29 and is indicative of emission from an active galactic nucleus. The radio luminosity is consistent with the average luminosity of the lower redshift BCG s le, but the flux densities are 6σ below the predicted values of the star-forming spectral energy distribution based on far infrared data. Our new fit fails to simultaneously describe the far infrared and radio fluxes. This, coupled with the fact that no other bright source is detected in the vicinity of the BCG implies that the star formation region, traced by the infrared emission, is extended or clumpy and not located directly within the BCG. Thus, we suggest that the star-forming core might not be driven by a single major wet merger, but rather by several smaller galaxies stripped of their gas or by a displaced cooling flow, although more data are needed to confirm any of those scenarios.
Publisher: SPIE
Date: 16-07-2010
DOI: 10.1117/12.856806
Publisher: SPIE
Date: 16-08-2000
DOI: 10.1117/12.395421
Publisher: Oxford University Press (OUP)
Date: 03-06-2013
DOI: 10.1093/MNRAS/STT811
Publisher: Oxford University Press (OUP)
Date: 29-08-2018
Publisher: EDP Sciences
Date: 07-2018
DOI: 10.1051/0004-6361/201731425
Abstract: We present a fully consistent catalog of local and global properties of host galaxies of 882 Type Ia supernovæ (SNIa) that were selected based on their light-curve properties, spanning the redshift range 0.01 z 1. This catalog corresponds to a preliminary version of the compilation s le and includes Supernova Legacy Survey (SNLS) 5-year data, Sloan Digital Sky Survey (SDSS), and low-redshift surveys. We measured low- and moderate-redshift host galaxy photometry in SDSS stacked and single-epoch images and used spectral energy distribution fitting techniques to derive host properties such as stellar mass and U − V rest-frame colors the latter are an indicator of the luminosity-weighted age of the stellar population in a galaxy. We combined these results with high-redshift host photometry from the SNLS survey and thus obtained a consistent catalog of host stellar masses and colors across a wide redshift range. We also estimated the local observed fluxes at the supernova location within a proper distance radius of 3 kpc, corresponding to the SNLS imaging resolution, and transposed them into local U − V rest-frame colors. This is the first time that local environments surrounding SNIa have been measured at redshifts spanning the entire Hubble diagram. Selecting SNIa based on host photometry quality, we then performed cosmological fits using local color as a third standardization variable, for which we split the s le at the median value. We find a local color step significance of − 0.091 ± 0.013 mag (7 σ ), which effect is as significant as the maximum mass step effect. This indicates that the remaining luminosity variations in SNIa s les can be reduced with a third standardization variable that takes the environment into account. Correcting for the maximum mass step correction of − 0.094 ± 0.013 mag, we find a local color effect of − 0.057 ± 0.012 mag (5 σ ), which shows that additional information is provided by the close environment of SNIa. Departures from the initial choices were investigated and showed that the local color effect is still present, although less pronounced. We discuss the possible implications for cosmology and find that using the local color in place of the stellar mass results in a change in the measured value of the dark energy equation-of-state parameter of 0.6%. Standardization using local U − V color in addition to stretch and color reduces the total dispersion in the Hubble diagram from 0.15 to 0.14 mag. This will be of tremendous importance for the forthcoming SNIa surveys, and in particular for the Large Synoptic Survey Telescope (LSST), for which uncertainties on the dark energy equation of state will be comparable to the effects reported here.
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B408814J
Abstract: A member of a new class of novel macrocycles possessing both polyether and phenolic functionalities, forms dimers in both the solid-state and in solution when exposed to chloroform, dichloromethane or toluene, but does not self-associate in the presence of dimethyl sulfoxide.
Publisher: EDP Sciences
Date: 20-01-2005
Publisher: American Physical Society (APS)
Date: 30-08-2016
Publisher: Oxford University Press (OUP)
Date: 19-05-2016
Publisher: American Astronomical Society
Date: 17-11-2009
Publisher: Oxford University Press (OUP)
Date: 09-02-2018
DOI: 10.1093/MNRAS/STY355
Publisher: EDP Sciences
Date: 27-08-2009
Publisher: Institution of Engineering and Technology (IET)
Date: 2010
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/CH04272
Abstract: There has been an explosion of interest in ionic liquids in the last five years that has resulted in the discovery of a vast number of new ionic liquids with a wide range of interesting applications. Although ionic liquids are invariably described as highly stable green solvents, thorough investigations quantifying their purity, stability, biodegradability, and toxicity have lagged behind the pace of other research in the area. This review addresses these key issues and summarizes the approaches that have been developed for recycling ionic liquids.
Publisher: Oxford University Press (OUP)
Date: 03-06-2022
Abstract: Cosmological analyses of s les of photometrically identified type Ia supernovae (SNe Ia) depend on understanding the effects of ‘contamination’ from core-collapse and peculiar SN Ia events. We employ a rigorous analysis using the photometric classifier SuperNNova on state-of-the-art simulations of SN s les to determine cosmological biases due to such ‘non-Ia’ contamination in the Dark Energy Survey (DES) 5-yr SN s le. Depending on the non-Ia SN models used in the SuperNNova training and testing s les, contamination ranges from 0.8 to 3.5 per cent, with a classification efficiency of 97.7–99.5 per cent. Using the Bayesian Estimation Applied to Multiple Species (BEAMS) framework and its extension BBC (‘BEAMS with Bias Correction’), we produce a redshift-binned Hubble diagram marginalized over contamination and corrected for selection effects, and use it to constrain the dark energy equation-of-state, w. Assuming a flat universe with Gaussian ΩM prior of 0.311 ± 0.010, we show that biases on w are & .008 when using SuperNNova, with systematic uncertainties associated with contamination around 10 per cent of the statistical uncertainty on w for the DES-SN s le. An alternative approach of discarding contaminants using outlier rejection techniques (e.g. Chauvenet’s criterion) in place of SuperNNova leads to biases on w that are larger but still modest (0.015–0.03). Finally, we measure biases due to contamination on w0 and wa (assuming a flat universe), and find these to be & .009 in w0 and & .108 in wa, 5 to 10 times smaller than the statistical uncertainties for the DES-SN s le.
Publisher: Oxford University Press (OUP)
Date: 16-08-2016
Publisher: Oxford University Press (OUP)
Date: 04-2014
DOI: 10.1093/PASJ/PSU024
Publisher: Elsevier BV
Date: 10-2018
Publisher: Springer Science and Business Media LLC
Date: 03-1998
DOI: 10.1038/32711
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B518132A
Publisher: Oxford University Press (OUP)
Date: 03-08-2021
Abstract: SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 c aigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of $\\sim 50{\\!-\\!}290\\, {\\rm R}_{\\odot }$, and an envelope mass of $\\sim 0{\\!-\\!}1.7\\, {\\rm M}_{\\odot }$. SN 2017jgh likely had a shock velocity of ∼7500−10 300 km s−1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of $\\sim 50{\\!-\\!}330\\, {\\rm R}_{\\odot }$, an envelope mass of $\\sim 0.3{\\!-\\!}1.7\\, {\\rm M}_{\\odot }$ and a shock velocity of ∼9000−15 000 km s−1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated.
Publisher: EDP Sciences
Date: 27-01-2006
Publisher: American Astronomical Society
Date: 06-02-2012
Publisher: Elsevier BV
Date: 03-2007
Publisher: Elsevier BV
Date: 2007
Publisher: EDP Sciences
Date: 03-2004
Publisher: Oxford University Press (OUP)
Date: 05-06-2021
Abstract: The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y & 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the ProFound image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 $\\mu$m. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.
Publisher: American Astronomical Society
Date: 24-11-2010
Publisher: American Astronomical Society
Date: 10-2022
Abstract: Current and future cosmological analyses with Type Ia supernovae (SNe Ia) face three critical challenges: (i) measuring the redshifts from the SNe or their host galaxies (ii) classifying the SNe without spectra and (iii) accounting for correlations between the properties of SNe Ia and their host galaxies. We present here a novel approach that addresses each of these challenges. In the context of the Dark Energy Survey (DES), we analyze an SN Ia s le with host galaxies in the redMaGiC galaxy catalog, a selection of luminous red galaxies. redMaGiC photo- z estimates are expected to be accurate to σ Δ z /(1+ z ) ∼ 0.02. The DES-5YR photometrically classified SN Ia s le contains approximately 1600 SNe, and 125 of these SNe are in redMaGiC galaxies. We demonstrate that redMaGiC galaxies almost exclusively host SNe Ia, reducing concerns relating to classification uncertainties. With this subs le, we find similar Hubble scatter (to within ∼0.01 mag) using photometric redshifts in place of spectroscopic redshifts. With detailed simulations, we show that the bias due to using redMaGiC photo- z s on the measurement of the dark energy equation of state w is up to Δ w ∼ 0.01–0.02. With real data, we measure a difference in w when using the redMaGiC photo- z s versus the spec- z s of Δ w = 0.005. Finally, we discuss how SNe in redMaGiC galaxies appear to comprise a more standardizable population, due to a weaker relation between color and luminosity ( β ) compared to the DES-3YR population by ∼5 σ . These results establish the feasibility of performing redMaGiC SN cosmology with photometric survey data in the absence of spectroscopic data.
Publisher: American Physical Society (APS)
Date: 21-02-2023
Publisher: American Astronomical Society
Date: 10-06-2006
DOI: 10.1086/503533
Publisher: Oxford University Press (OUP)
Date: 23-06-2020
Abstract: We report the identification of a low-mass active galactic nucleus (AGN), DES J0218−0430, in a redshift z = 0.823 galaxy in the Dark Energy Survey (DES) Supernova field. We select DES J0218−0430 as an AGN candidate by characterizing its long-term optical variability alone based on DES optical broad-band light curves spanning over 6 yr. An archival optical spectrum from the fourth phase of the Sloan Digital Sky Survey shows both broad Mg ii and broad H β lines, confirming its nature as a broad-line AGN. Archival XMM–Newton X-ray observations suggest an intrinsic hard X-ray luminosity of $L_{{\\rm 2-12\\, keV}}\\approx 7.6\\pm 0.4\\times 10^{43}$ erg s−1, which exceeds those of the most X-ray luminous starburst galaxies, in support of an AGN driving the optical variability. Based on the broad H β from SDSS spectrum, we estimate a virial black hole (BH) mass of M• ≈ 106.43–106.72 M⊙ (with the error denoting the systematic uncertainty from different calibrations), consistent with the estimation from OzDES, making it the lowest mass AGN with redshift & 0.4 detected in optical. We estimate the host galaxy stellar mass to be M* ≈ 1010.5 ± 0.3 M⊙ based on modelling the multiwavelength spectral energy distribution. DES J0218−0430 extends the M•–M* relation observed in luminous AGNs at z ∼ 1 to masses lower than being probed by previous work. Our work demonstrates the feasibility of using optical variability to identify low-mass AGNs at higher redshift in deeper synoptic surveys with direct implications for the upcoming Legacy Survey of Space and Time at Vera C. Rubin Observatory.
Publisher: American Astronomical Society
Date: 24-09-2020
Publisher: Oxford University Press (OUP)
Date: 26-07-2017
Publisher: EDP Sciences
Date: 25-02-2011
Publisher: American Astronomical Society
Date: 11-2005
DOI: 10.1086/444595
Publisher: American Astronomical Society
Date: 2004
DOI: 10.1086/379857
Publisher: EDP Sciences
Date: 11-2010
Publisher: EDP Sciences
Date: 08-2014
Publisher: Cambridge University Press (CUP)
Date: 08-2009
DOI: 10.1017/S1743921310003224
Abstract: We present a measurement of the rate of high-z Type Ia supernovae (SNe Ia) using multi-epoch observations of Subaru/XMM-Newton Deep Field (SXDF) with Suprime-Cam on the Subaru Telescope. Although SNe Ia are regarded as a standard candle, progenitor systems of SNe Ia have not been resolved yet. One of the key parameters to show the progenitor systems by observations is the delay time distribution between the binary system formation and subsequent SN explosion. Recently, a wide range of delay time is studied by SN Ia rates compared with an assumed cosmic star formation history. If SNe Ia with short delay time are dominant, the cosmic SN Ia rate evolution should closely trace that of the cosmic star formation. In order to detect a lot of high-z SNe Ia and measure SN Ia rates, we repeatedly carried out wide and deep imaging observations in the í -band with Suprime-Cam in 2002 (FoV~1 deg 2 , m i 25.5 mag). We obtained detailed light curves of the variable objects, and 50 objects are classified as SNe Ia using the light curve fitting method at the redshift range of 0.2 z 1.3. In order to check the completeness and contamination of the light curve classification method, we performed Monte Carlo simulations and generated ~100,000 light curves of SNe Ia and II from templates. The control time and detection efficiency of the SN survey are also calculated using the artificial light curves. We derived an increasing trend of rates at around z ~ 1.2. Our results are almost consistent with other SN Ia rate results from low-z to high-z. Our results are the first results of high-z SN Ia rates with large statistics using light curves obtained by ground based telescopes, and give us visions of the SN rate studies for the future.
Publisher: Oxford University Press (OUP)
Date: 12-2021
Abstract: We present multiwavelength spectral and temporal variability analysis of PKS 0027-426 using optical griz observations from Dark Energy Survey between 2013 and 2018 and VEILS Optical Light curves of Extragalactic TransienT Events (VOILETTE) between 2018 and 2019 and near-infrared (NIR) JKs observations from Visible and Infrared Survey Telescope for Astronomy Extragalactic Infrared Legacy Survey (VEILS) between 2017 and 2019. Multiple methods of cross-correlation of each combination of light curve provides measurements of possible lags between optical–optical, optical–NIR, and NIR–NIR emission, for each observation season and for the entire observational period. Inter-band time lag measurements consistently suggest either simultaneous emission or delays between emission regions on time-scales smaller than the cadences of observations. The colour–magnitude relation between each combination of filters was also studied to determine the spectral behaviour of PKS 0027-426. Our results demonstrate complex colour behaviour that changes between bluer when brighter, stable when brighter, and redder when brighter trends over different time-scales and using different combinations of optical filters. Additional analysis of the optical spectra is performed to provide further understanding of this complex spectral behaviour.
Publisher: American Astronomical Society
Date: 12-10-2017
Publisher: No publisher found
Date: 2003
DOI: 10.1007/10857580\_58
Publisher: Cambridge University Press (CUP)
Date: 07-2015
DOI: 10.1017/S1743921314009910
Abstract: One of the most characteristic features of galaxy clusters is the so-called “red sequence” (RS) of early-type galaxies. Since these galaxies are, in general, devoid of gas and dust, their red colors are mainly a consequence of their passive nature. However, the physical mechanisms responsible for quenching their star formation, thus originating the RS, are poorly understood. Environmental effects should play a significant role in the formation of the RS by transforming the observed galaxy properties from late to early-type ones. In this respect, we have initiated a KMOS program aimed at studying the kinematical structure of cluster galaxies at 0.8 z 1.7 in an effort to disentangle the physical mechanisms responsible for cluster galaxy evolution and the formation of the RS.
Publisher: EDP Sciences
Date: 02-2021
DOI: 10.1051/0004-6361/202039063
Abstract: We present a joint cosmological analysis of weak gravitational lensing observations from the Kilo-Degree Survey (KiDS-1000), with redshift-space galaxy clustering observations from the Baryon Oscillation Spectroscopic Survey (BOSS) and galaxy-galaxy lensing observations from the overlap between KiDS-1000, BOSS, and the spectroscopic 2-degree Field Lensing Survey. This combination of large-scale structure probes breaks the degeneracies between cosmological parameters for in idual observables, resulting in a constraint on the structure growth parameter S 8 = σ 8 √(Ω m /0.3) = 0.766 −0.014 +0.020 , which has the same overall precision as that reported by the full-sky cosmic microwave background observations from Planck . The recovered S 8 litude is low, however, by 8.3 ± 2.6% relative to Planck . This result builds from a series of KiDS-1000 analyses where we validate our methodology with variable depth mock galaxy surveys, our lensing calibration with image simulations and null-tests, and our optical-to-near-infrared redshift calibration with multi-band mock catalogues and a spectroscopic-photometric clustering analysis. The systematic uncertainties identified by these analyses are folded through as nuisance parameters in our cosmological analysis. Inspecting the offset between the marginalised posterior distributions, we find that the S 8 -difference with Planck is driven by a tension in the matter fluctuation litude parameter, σ 8 . We quantify the level of agreement between the cosmic microwave background and our large-scale structure constraints using a series of different metrics, finding differences with a significance ranging between ∼3 σ , when considering the offset in S 8 , and ∼2 σ , when considering the full multi-dimensional parameter space.
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201730479
Abstract: Context. This work is part of a series of studies focusing on the environment and the properties of the X-ray selected active galactic nuclei (AGN) population from the XXL survey. The present survey, given its large area, continuity, extensive multiwavelength coverage, and large-scale structure information, is ideal for this kind of study. Here, we focus on the XXL-South (XXL-S) field. Aims. Our main aim is to study the environment of the various types of X-ray selected AGN and investigate its possible role in AGN triggering and evolution. Methods. We studied the large-scale ( Mpc) environment up to redshift z = 1 using the nearest neighbour distance method to compare various pairs of AGN types. We also investigated the small-scale environment ( .4 Mpc) by calculating the local overdensities of optical galaxies. In addition, we built a catalogue of AGN concentrations with two or more members using the hierarchical clustering method and we correlated them with the X-ray galaxy clusters detected in the XXL survey. Results. It is found that radio detected X-ray sources are more obscured than non-radio ones, though not all radio sources are obscured AGN. We did not find any significant differences in the large-scale clustering between luminous and faint X-ray AGN, or between obscured and unobscured ones, or between radio and non-radio sources. At local scales ( .4 Mpc), AGN typically reside in overdense regions, compared to non-AGN however, no differences were found between the various types of AGN. A majority of AGN concentrations with two or more members are found in the neighbourhood of X-ray galaxy clusters within –45 Mpc. Our results suggest that X-ray AGN are typically located in supercluster filaments, but they are also found in over- and underdense regions.
Publisher: American Astronomical Society
Date: 03-08-2020
Publisher: American Astronomical Society
Date: 20-09-2002
DOI: 10.1086/342129
Publisher: SPIE
Date: 09-08-2016
DOI: 10.1117/12.2232107
Publisher: Oxford University Press (OUP)
Date: 14-06-2018
Publisher: Oxford University Press (OUP)
Date: 05-08-2021
Abstract: Reverberation mapping is a robust method to measure the masses of supermassive black holes outside of the local Universe. Measurements of the radius–luminosity (R−L) relation using the Mg ii emission line are critical for determining these masses near the peak of quasar activity at z ≈ 1−2, and for calibrating secondary mass estimators based on Mg ii that can be applied to large s les with only single-epoch spectroscopy. We present the first nine Mg ii lags from our 5-yr Australian Dark Energy Survey reverberation mapping programme, which substantially improves the number and quality of Mg ii lag measurements. As the Mg ii feature is somewhat blended with iron emission, we model and subtract both the continuum and iron contamination from the multiepoch spectra before analysing the Mg ii line. We also develop a new method of quantifying correlated spectroscopic calibration errors based on our numerous, contemporaneous observations of F-stars. The lag measurements for seven of our nine sources are consistent with both the H β and Mg ii R−L relations reported by previous studies. Our simulations verify the lag reliability of our nine measurements, and we estimate that the median false positive rate of the lag measurements is $4{{\\ \\rm per\\ cent}}$.
Publisher: EDP Sciences
Date: 31-07-2006
Publisher: Oxford University Press (OUP)
Date: 30-11-2020
Abstract: The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will observe several Deep Drilling Fields (DDFs) to a greater depth and with a more rapid cadence than the main survey. In this paper, we describe the ‘DeepDrill’ survey, which used the Spitzer Space Telescope Infrared Array Camera (IRAC) to observe three of the four currently defined DDFs in two bands, centred on 3.6 and 4.5 μm. These observations expand the area that was covered by an earlier set of observations in these three fields by the Spitzer Extragalactic Representative Volume Survey (SERVS). The combined DeepDrill and SERVS data cover the footprints of the LSST DDFs in the Extended Chandra Deep Field–South (ECDFS) field, the ELAIS-S1 field (ES1), and the XMM-Large-Scale Structure Survey field (XMM-LSS). The observations reach an approximate 5σ point-source depth of 2 μJy (corresponding to an AB magnitude of 23.1 sufficient to detect a 10$^{11} \\, \\mathrm{M}_{\\odot}$ galaxy out to z ≈ 5) in each of the two bands over a total area of $\\approx 29\\,$ deg2. The dual-band catalogues contain a total of 2.35 million sources. In this paper, we describe the observations and data products from the survey, and an overview of the properties of galaxies in the survey. We compare the source counts to predictions from the Shark semi-analytic model of galaxy formation. We also identify a population of sources with extremely red ([3.6]−[4.5] & .2) colours which we show mostly consists of highly obscured active galactic nuclei.
Publisher: EDP Sciences
Date: 06-2010
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present a recalibration of the photometric systems in the Pantheon+ s le of Type Ia supernovae (SNe Ia) including those in the SH0ES distance-ladder measurement of H 0 . We utilize the large and uniform sky coverage of the public Pan-STARRS stellar photometry catalog to cross calibrate against tertiary standards released by in idual SN Ia surveys. The most significant updates over the “SuperCal” cross calibration used for the previous Pantheon and SH0ES analyses are: (1) expansion of the number of photometric systems (now 25) and filters (now 105), (2) solving for all filter offsets in all systems simultaneously to produce a calibration uncertainty covariance matrix for cosmological-model constraints, and (3) accounting for the change in the fundamental flux calibration of the Hubble Space Telescope CALSPEC standards from previous versions on the order of 1.5% over a Δ λ of 4000 Å. We retrain the SALT2 model and find that our new model coupled with the new calibration of the light curves themselves causes a net distance modulus change ( d μ / dz ) of 0.04 mag over the redshift range 0 z 1. We introduce a new formalism to determine the systematic impact on cosmological inference by propagating the covariance in the fitted calibration offsets through retraining simultaneously with light-curve fitting and find a total calibration uncertainty impact of σ w = 0.013 roughly half the size of the s le statistical uncertainty. Similarly, we find the systematic SN calibration contribution to the SH0ES H 0 uncertainty is less than 0.2 km s −1 Mpc −1 , suggesting that SN Ia calibration cannot resolve the current level of the “Hubble Tension.”
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201630129
Abstract: The 2.1 GHz radio source catalogue of the 25 deg 2 ultimate XMM extragalactic survey south (XXL-S) field, observed with the Australia Telescope Compact Array (ATCA), is presented. The final radio mosaic achieved a resolution of ~ 4.8″ and a median rms noise of σ ≈ 41 μ Jy/beam. To date, this is the largest area radio survey to reach this flux density level. A total of 6350 radio components above 5 σ are included in the component catalogue, 26.4% of which are resolved. Of these components, 111 were merged together to create 48 multiple-component radio sources, resulting in a total of 6287 radio sources in the source catalogue, 25.9% of which were resolved. A survival analysis revealed that the median spectral index of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is α = −0.75, consistent with the values of − 0.7 to − 0.8 commonly used to characterise radio spectral energy distributions of active galactic nuclei. The 2.1 GHz and 1.4 GHz differential radio source counts are presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts show good agreement with the other surveys.
Publisher: American Astronomical Society
Date: 31-01-2023
Abstract: We present early observations and analysis of the double-peaked Type IIb supernova (SN IIb) SN 2021zby. TESS captured the prominent early shock-cooling peak of SN 2021zby within the first ∼10 days after explosion with a 30 minute cadence. We present optical and near-infrared spectral series of SN 2021zby, including three spectra during the shock-cooling phase. Using a multiband model fit, we find that the inferred properties of its progenitor are consistent with a red supergiant or yellow supergiant, with an envelope mass of ∼0.30–0.65 M ⊙ and an envelope radius of ∼120–300 R ⊙ . These inferred progenitor properties are similar to those of other SNe IIb with a double-peaked feature, such as SNe 1993J, 2011dh, 2016gkg, and 2017jgh. This study further validates the importance of the high cadence and early coverage in resolving the shape of the shock-cooling light curve, while the multiband observations, particularly UV, are also necessary to fully constrain the progenitor properties.
Publisher: Oxford University Press (OUP)
Date: 26-06-2017
Publisher: EDP Sciences
Date: 08-2014
Publisher: EDP Sciences
Date: 22-05-2008
Publisher: American Astronomical Society
Date: 21-05-2010
Publisher: EDP Sciences
Date: 11-08-2009
Publisher: American Astronomical Society
Date: 07-04-2020
Publisher: Oxford University Press (OUP)
Date: 19-01-2012
Publisher: Oxford University Press (OUP)
Date: 11-09-2021
Abstract: We measure the rate of environmentally driven star formation quenching in galaxies at z ∼ 1, using eleven massive ($M\\approx 2\\times 10^{14}\\, \\mathrm{M}_\\odot$) galaxy clusters spanning a redshift range 1.0 & z & 1.4 from the GOGREEN s le. We identify three different types of transition galaxies: ‘green valley’ (GV) galaxies identified from their rest-frame (NUV − V) and (V − J) colours ‘blue quiescent’ (BQ) galaxies, found at the blue end of the quiescent sequence in (U − V) and (V − J) colour and spectroscopic post-starburst (PSB) galaxies. We measure the abundance of these galaxies as a function of stellar mass and environment. For high-stellar mass galaxies (log M/M⊙ & 10.5) we do not find any significant excess of transition galaxies in clusters, relative to a comparison field s le at the same redshift. It is likely that such galaxies were quenched prior to their accretion in the cluster, in group, filament, or protocluster environments. For lower stellar mass galaxies (9.5 & log M/M⊙ & 10.5) there is a small but significant excess of transition galaxies in clusters, accounting for an additional ∼5–10 per cent of the population compared with the field. We show that our data are consistent with a scenario in which 20–30 per cent of low-mass, star-forming galaxies in clusters are environmentally quenched every Gyr, and that this rate slowly declines from z = 1 to z = 0. While environmental quenching of these galaxies may include a long delay time during which star formation declines slowly, in most cases this must end with a rapid (τ & 1 Gyr) decline in star formation rate.
Publisher: Elsevier BV
Date: 04-2016
Publisher: SPIE
Date: 14-07-2008
DOI: 10.1117/12.788209
Publisher: American Astronomical Society
Date: 16-09-2019
Publisher: EDP Sciences
Date: 30-06-2005
Publisher: Oxford University Press (OUP)
Date: 19-05-2020
Abstract: The 5-yr Dark Energy Survey Supernova Programme (DES-SN) is one of the largest and deepest transient surveys to date in terms of volume and number of supernovae. Identifying and characterizing the host galaxies of transients plays a key role in their classification, the study of their formation mechanisms, and the cosmological analyses. To derive accurate host galaxy properties, we create depth-optimized coadds using single-epoch DES-SN images that are selected based on sky and atmospheric conditions. For each of the five DES-SN seasons, a separate coadd is made from the other four seasons such that each SN has a corresponding deep coadd with no contaminating SN emission. The coadds reach limiting magnitudes of order ∼27 in g band, and have a much smaller magnitude uncertainty than the previous DES-SN host templates, particularly for faint objects. We present the resulting multiband photometry of host galaxies for s les of spectroscopically confirmed type Ia (SNe Ia), core-collapse (CCSNe), and superluminous (SLSNe) as well as rapidly evolving transients (RETs) discovered by DES-SN. We derive host galaxy stellar masses and probabilistically compare stellar-mass distributions to s les from other surveys. We find that the DES spectroscopically confirmed s le of SNe Ia selects preferentially fewer high-mass hosts at high-redshift compared to other surveys, while at low redshift the distributions are consistent. DES CCSNe and SLSNe hosts are similar to other s les, while RET hosts are unlike the hosts of any other transients, although these differences have not been disentangled from selection effects.
Publisher: Oxford University Press (OUP)
Date: 22-02-2018
DOI: 10.1093/MNRAS/STY466
Publisher: Springer Berlin Heidelberg
Date: 2008
Publisher: Springer Science and Business Media LLC
Date: 24-01-2014
DOI: 10.1007/S00726-014-1672-8
Abstract: Recently, we reported a new way of performing 2-DE, called P-dimensional electrophoresis (2-PE). In this approach, the second dimension is achieved in a radial gel which can accommodate up to six 7 cm long IPG strips simultaneously, improving reproducibility and throughput power in respect to 2-DE. Nevertheless, 2-PE was up to now limited to the use of only short strips because of technical difficulties. Here, we describe how to load longer strips (e.g., 18-24 cm) on 2-PE and report some representative images for a qualitative assessment.
Publisher: Oxford University Press (OUP)
Date: 31-10-2018
Publisher: American Astronomical Society
Date: 20-04-2015
Publisher: Oxford University Press (OUP)
Date: 24-11-2022
Abstract: Recent observations have shown that the environmental quenching of galaxies at z ∼ 1 is qualitatively different to that in the local Universe. However, the physical origin of these differences has not yet been elucidated. In addition, while low-redshift comparisons between observed environmental trends and the predictions of cosmological hydrodynamical simulations are now routine, there have been relatively few comparisons at higher redshifts to date. Here we confront three state-of-the-art suites of simulations (BAHAMAS+MACSIS, EAGLE+Hydrangea, IllustrisTNG) with state-of-the-art observations of the field and cluster environments from the COSMOS/UltraVISTA and GOGREEN surveys, respectively, at z ∼ 1 to assess the realism of the simulations and gain insight into the evolution of environmental quenching. We show that while the simulations generally reproduce the stellar content and the stellar mass functions of quiescent and star-forming galaxies in the field, all the simulations struggle to capture the observed quenching of satellites in the cluster environment, in that they are overly efficient at quenching low-mass satellites. Furthermore, two of the suites do not sufficiently quench the highest mass galaxies in clusters, perhaps a result of insufficient feedback from AGN. The origin of the discrepancy at low stellar masses ($M_* \\lesssim 10^{10}$ M⊙), which is present in all the simulations in spite of large differences in resolution, feedback implementations, and hydrodynamical solvers, is unclear. The next generation of simulations, which will push to significantly higher resolution and also include explicit modelling of the cold interstellar medium, may help us to shed light on the low-mass tension.
Publisher: SPIE
Date: 12-2002
DOI: 10.1117/12.459498
Publisher: Springer Science and Business Media LLC
Date: 10-2002
DOI: 10.1038/NATURE01121
Publisher: Oxford University Press (OUP)
Date: 10-09-2020
Abstract: We study the star formation histories (SFHs) and mass-weighted ages of 331 UVJ-selected quiescent galaxies in 11 galaxy clusters and in the field at 1 & z & 1.5 from the Gemini Observations of Galaxies in Rich Early ENvironments (GOGREEN) survey. We determine the SFHs of in idual galaxies by simultaneously fitting rest-frame optical spectroscopy and broad-band photometry to stellar population models. We confirm that the SFHs are consistent with more massive galaxies having on average earlier formation times. Comparing galaxies found in massive clusters with those in the field, we find galaxies with M* & 1011.3 M⊙ in the field have more extended SFHs. From the SFHs we calculate the mass-weighted ages, and compare age distributions of galaxies between the two environments, at fixed mass. We constrain the difference in mass-weighted ages between field and cluster galaxies to $0.31_{^{-0.33}}^{_{+0.51}}$ Gyr, in the sense that cluster galaxies are older. We place this result in the context of two simple quenching models and show that neither environmental quenching based on time since infall (without pre-processing) nor a difference in formation times alone can reproduce both the average age difference and relative quenched fractions. This is distinctly different from local clusters, for which the majority of the quenched population is consistent with having been environmentally quenched upon infall. Our results suggest that quenched population in galaxy clusters at z & 1 has been driven by different physical processes than those at play at z = 0.
Publisher: Oxford University Press (OUP)
Date: 21-05-2019
Abstract: We present a s le of 21 hydrogen-free superluminous supernovae (SLSNe-I) and one hydrogen-rich SLSN (SLSN-II) detected during the five-year Dark Energy Survey (DES). These SNe, located in the redshift range 0.220 & z & 1.998, represent the largest homogeneously selected s le of SLSN events at high redshift. We present the observed g, r, i, z light curves for these SNe, which we interpolate using Gaussian processes. The resulting light curves are analysed to determine the luminosity function of SLSNe-I, and their evolutionary time-scales. The DES SLSN-I s le significantly broadens the distribution of SLSN-I light-curve properties when combined with existing s les from the literature. We fit a magnetar model to our SLSNe, and find that this model alone is unable to replicate the behaviour of many of the bolometric light curves. We search the DES SLSN-I light curves for the presence of initial peaks prior to the main light-curve peak. Using a shock breakout model, our Monte Carlo search finds that 3 of our 14 events with pre-max data display such initial peaks. However, 10 events show no evidence for such peaks, in some cases down to an absolute magnitude of & −16, suggesting that such features are not ubiquitous to all SLSN-I events. We also identify a red pre-peak feature within the light curve of one SLSN, which is comparable to that observed within SN2018bsz.
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: No publisher found
Date: 2005
DOI: 10.1007/10828557\_11
Publisher: Oxford University Press (OUP)
Date: 18-05-2022
Abstract: We study the optical gri photometric variability of a s le of 190 quasars within the SDSS Stripe 82 region that have long-term photometric coverage during ∼1998−2020 with SDSS, PanSTARRS-1, the Dark Energy Survey, and dedicated follow-up monitoring with Blanco 4m/DECam. With on average ∼200 nightly epochs per quasar per filter band, we improve the parameter constraints from a D ed Random Walk (DRW) model fit to the light curves over previous studies with 10–15 yr baselines and ≲ 100 epochs. We find that the average d ing time-scale τDRW continues to rise with increased baseline, reaching a median value of ∼750 d (g band) in the rest frame of these quasars using the 20-yr light curves. Some quasars may have gradual, long-term trends in their light curves, suggesting that either the DRW fit requires very long baselines to converge, or that the underlying variability is more complex than a single DRW process for these quasars. Using a subset of quasars with better-constrained τDRW (less than 20 per cent of the baseline), we confirm a weak wavelength dependence of τDRW∝λ0.51 ± 0.20. We further quantify optical variability of these quasars over days to decades time-scales using structure function (SF) and power spectrum density (PSD) analyses. The SF and PSD measurements qualitatively confirm the measured (hundreds of days) d ing time-scales from the DRW fits. However, the ensemble PSD is steeper than that of a DRW on time-scales less than ∼ a month for these luminous quasars, and this second break point correlates with the longer DRW d ing time-scale.
Publisher: Oxford University Press (OUP)
Date: 30-09-2020
Abstract: We calculate H α-based star formation rates and determine the star formation rate–stellar mass relation for members of three Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) clusters at z ∼ 1.6 and serendipitously identified field galaxies at similar redshifts to the clusters. We find similar star formation rates in cluster and field galaxies throughout our range of stellar masses. The results are comparable to those seen in other clusters at similar redshifts, and consistent with our previous photometric evidence for little quenching activity in clusters. One possible explanation for our results is that galaxies in our z ∼ 1.6 clusters have been accreted too recently to show signs of environmental quenching. It is also possible that the clusters are not yet dynamically mature enough to produce important environmental quenching effects shown to be important at low redshift, such as ram-pressure stripping or harassment.
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.40
Abstract: As the scale of cosmological surveys increases, so does the complexity in the analyses. This complexity can often make it difficult to derive the underlying principles, necessitating statistically rigorous testing to ensure the results of an analysis are consistent and reasonable. This is particularly important in multi-probe cosmological analyses like those used in the Dark Energy Survey (DES) and the upcoming Legacy Survey of Space and Time, where accurate uncertainties are vital. In this paper, we present a statistically rigorous method to test the consistency of contours produced in these analyses and apply this method to the Pippin cosmological pipeline used for type Ia supernova cosmology with the DES. We make use of the Neyman construction, a frequentist methodology that leverages extensive simulations to calculate confidence intervals, to perform this consistency check. A true Neyman construction is too computationally expensive for supernova cosmology, so we develop a method for approximating a Neyman construction with far fewer simulations. We find that for a simulated dataset, the 68% contour reported by the Pippin pipeline and the 68% confidence region produced by our approximate Neyman construction differ by less than a percent near the input cosmology however, they show more significant differences far from the input cosmology, with a maximal difference of 0.05 in $\\Omega_{M}$ and 0.07 in w . This ergence is most impactful for analyses of cosmological tensions, but its impact is mitigated when combining supernovae with other cross-cutting cosmological probes, such as the cosmic microwave background.
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201832970
Abstract: The XMM-XXL Survey spans two fields of 25 deg 2 each observed for more than 6 Ms with XMM, which provided a s le of tens of thousands of point sources with a flux limit of ~2.2 × 10 −15 and ~1.4 × 10 −14 erg s −1 cm 2 , corresponding to 50% of the area curve, in the soft band (0.5–2 keV) and hard band (2–10 keV), respectively. In this paper we present the spatial clustering properties of ~3100 and ~1900 X-ray active galactic nuclei (AGNs) in the soft and hard bands, respectively, which have been spectroscopically observed with the AAOmega facility. This s le is 90% redshift complete down to an optical magnitude limit of r ≲ 21.8. The sources span the redshift interval 0 z 5.2, although in the current analysis we limit our s les to z ≤ 3, with corresponding s le median values of z ̅ ≃ 0.96 and 0.79 for the soft band and hard band, respectively. We employ the projected two-point correlation function to infer the spatial clustering and find a correlation length r 0 = 7.0(±0.34) and 6.42(±0.42) h −1 Mpc, respectively, for the soft- and hard-band detected sources with a slope for both cases of γ = 1.44(±0.1). The power-law clustering was detected within comoving separations of 1 and ~25 h −1 Mpc. These results, as well as those derived in two separate redshift ranges, provide bias factors of the corresponding AGN host dark matter halos that are consistent with a halo mass of log 10 [ M h ∕( h −1 M ⊙ )] = 13.04 ± 0.06, confirming the results of most recent studies based on smaller X-ray AGN s les.
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201832974
Abstract: Context. We present the results of a study of the active galactic nucleus (AGN) density in a homogeneous and well-studied s le of 167 bona fide X-ray galaxy clusters (0.1 z 0.5) from the XXL Survey, from the cluster core to the outskirts (up to 6 r 500 ). The results can provide evidence of the physical mechanisms that drive AGN and galaxy evolution within clusters, testing the efficiency of ram pressure gas stripping and galaxy merging in dense environments. Aims. The XXL cluster s le mostly comprises poor and moderately rich structures ( M = 10 13 –4 × 10 14 M ⊙ ), a poorly studied population that bridges the gap between optically selected groups and massive X-ray selected clusters. Our aim is to statistically study the demographics of cluster AGNs as a function of cluster mass and host galaxy position. Methods. To investigate the effect of the environment on AGN activity, we computed the fraction of spectroscopically confirmed X-ray AGNs ( L X [0.5-10 keV] 10 42 erg cm −1 ) in bright cluster galaxies with M i * − 2 M M i * + 1, up to 6 r 500 radius. The corresponding field fraction was computed from 200 mock cluster catalogues with reshuffled positions within the XXL fields. To study the mass dependence and the evolution of the AGN population, we further ided the s le into low- and high-mass clusters (below and above 10 14 M ⊙ , respectively) and two redshift bins (0.1–0.28 and 0.28–0.5). Results. We detect a significant excess of X-ray AGNs, at the 95% confidence level, in low-mass clusters between 0.5 r 500 and 2 r 500 , which drops to the field value within the cluster cores ( r 0.5 r 500 ). In contrast, high-mass clusters present a decreasing AGN fraction towards the cluster centres, in agreement with previous studies. The high AGN fraction in the outskirts is caused by low-luminosity AGNs, up to L X [0.5-10 keV] = 10 43 erg cm −1 . It can be explained by a higher galaxy merging rate in low-mass clusters, where velocity dispersions are not high enough to prevent galaxy interactions and merging. Ram pressure stripping is possible in the cores of all our clusters, but probably stronger in deeper gravitational potentials. Compared with previous studies of massive or high-redshift clusters, we conclude that the AGN fraction in cluster galaxies anti-correlates strongly with cluster mass. The AGN fraction also increases with redshift, but at the same rate with the respective fraction in field galaxies.
Publisher: EDP Sciences
Date: 15-06-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B305401M
Publisher: American Institute of Physics
Date: 2007
DOI: 10.1063/1.2774890
Publisher: SPIE
Date: 12-07-2008
DOI: 10.1117/12.788676
Publisher: American Astronomical Society
Date: 05-1997
DOI: 10.1086/303973
Publisher: Springer Berlin Heidelberg
Publisher: EDP Sciences
Date: 05-2021
DOI: 10.1051/0004-6361/202039805
Abstract: We present constraints on extensions to the standard cosmological model of a spatially flat Universe governed by general relativity, a cosmological constant (Λ), and cold dark matter (CDM) by varying the spatial curvature Ω K , the sum of the neutrino masses ∑ m ν , the dark energy equation of state parameter w , and the Hu-Sawicki f ( R ) gravity f R 0 parameter. With the combined 3 × 2 pt measurements of cosmic shear from the Kilo-Degree Survey (KiDS-1000), galaxy clustering from the Baryon Oscillation Spectroscopic Survey (BOSS), and galaxy-galaxy lensing from the overlap between KiDS-1000, BOSS, and the spectroscopic 2-degree Field Lensing Survey, we find results that are fully consistent with a flat ΛCDM model with Ω K = 0.011 −0.057 +0.054 , ∑ m ν 1.76 eV (95% CL), and w = −0.99 −0.13 +0.11 . The f R 0 parameter is unconstrained in our fully non-linear f ( R ) cosmic shear analysis. Considering three different model selection criteria, we find no clear preference for either the fiducial flat ΛCDM model or any of the considered extensions. In addition to extensions to the flat ΛCDM parameter space, we also explore restrictions to common subsets of the flat ΛCDM parameter space by fixing the litude of the primordial power spectrum to the Planck best-fit value, as well as adding external data from supernovae and lensing of the cosmic microwave background (CMB). Neither the beyond-ΛCDM models nor the imposed restrictions explored in this analysis are able to resolve the ∼3 σ tension in S 8 between the 3 × 2 pt constraints and the Planck temperature and polarisation data, with the exception of w CDM, where the S 8 tension is resolved. The tension in the w CDM case persists, however, when considering the joint S 8 − w parameter space. The joint flat ΛCDM CMB lensing and 3 × 2 pt analysis is found to yield tight constraints on Ω m = 0.307 −0.013 +0.008 , σ 8 = 0.769 −0.010 +0.022 , and S 8 = 0.779 −0.013 +0.013 .
Publisher: Oxford University Press (OUP)
Date: 15-05-2020
Abstract: The Supernova Cosmology Project has conducted the ‘See Change’ programme, aimed at discovering and observing high-redshift (1.13 ≤ z ≤ 1.75) Type Ia supernovae (SNe Ia). We used multifilter Hubble Space Telescope (HST) observations of massive galaxy clusters with sufficient cadence to make the observed SN Ia light curves suitable for a cosmological probe of dark energy at z & 0.5. This See Change s le of SNe Ia with multi-colour light curves will be the largest to date at these redshifts. As part of the See Change programme, we obtained ground-based spectroscopy of each discovered transient and/or its host galaxy. Here, we present Very Large Telescope (VLT) spectra of See Change transient host galaxies, deriving their redshifts, and host parameters such as stellar mass and star formation rate. Of the 39 See Change transients/hosts that were observed with the VLT, we successfully determined the redshift for 26, including 15 SNe Ia at z & 0.97. We show that even in passive environments, it is possible to recover secure redshifts for the majority of SN hosts out to z = 1.5. We find that with typical exposure times of 3−4 h on an 8-m-class telescope we can recover ∼75 per cent of SN Ia redshifts in the range of 0.97 & z & 1.5. Furthermore, we show that the combination of HST photometry and VLT spectroscopy is able to provide estimates of host galaxy stellar mass that are sufficiently accurate for use in a mass-step correction in the cosmological analysis.
Publisher: Springer Berlin Heidelberg
Publisher: EDP Sciences
Date: 08-08-2008
Publisher: S. Karger AG
Date: 1994
DOI: 10.1159/000201173
Abstract: Trans fatty acids are produced in the manufacture of margarine, and these hydrogenated fatty acids may have a deleterious effect on the reduction in fasting levels of serum cholesterol anticipated from the feeding of cis polyunsaturated fatty acids. We undertook this study in rats to test the effect of feeding trans fatty acids on the intestinal uptake of glucose, fatty acids and cholesterol. Adult female Wistar rats were fed for 2 weeks semisynthetic, isocaloric diets containing no oleic acid (18:1), cis 18:1 or trans 18:1. There was no difference between the three dietary groups in the animals' food consumption or body weight gain. Rats fed trans 18:1 had an approximately 20% decline in the total weight of the ileum as compared with controls fed no 18:1, and therefore there was also a decline in the percentage of the ileal tissue comprised of mucosa. When comparing rats fed trans 18:1 with those fed cis 18:1 or no 18:1, there was no difference in the uptake of varying concentrations of D-glucose when expressed as nmol.100 mg tissue-1.min-1 or nmol.100 mg mucosal-1.min-1 for jejunum or for ileum. Also, there was no difference in the value of the maximal transport rate (Vmax), Michaelis constant (Km), or the contribution of passive uptake of glucose assessed with L-glucose. There was no diet-associated change in the jejunal or ileal uptake of a medium-chain length fatty acid (lauric acid), a long-chain length saturated fatty acid (palmitic acid), a monounsaturated fatty acid (oleic acid), two polyunsaturated fatty acids (linoleic and linolenic acids), or cholesterol. Thus, we conclude that 2 weeks' feeding of trans fatty acid to rats has no influence on the jejunal or ileal uptake of glucose, fatty acids or cholesterol.
Publisher: EDP Sciences
Date: 06-2021
DOI: 10.1051/0004-6361/202140564
Abstract: Context. The study of galaxy cluster mass profiles ( M ( r )) provides constraints on the nature of dark matter and on physical processes affecting the mass distribution. The study of galaxy cluster velocity anisotropy profiles ( β ( r )) informs the orbits of galaxies in clusters, which are related to their evolution. The combination of mass profiles and velocity anisotropy profiles allows us to determine the pseudo phase-space density profiles ( Q ( r )) numerical simulations predict that these profiles follow a simple power law in cluster-centric distance. Aims. We determine the mass, velocity anisotropy, and pseudo phase-space density profiles of clusters of galaxies at the highest redshifts investigated in detail to date. Methods. We exploited the combination of the GOGREEN and GCLASS spectroscopic data-sets for 14 clusters with mass M 200 ≥ 10 14 M ⊙ at redshifts 0.9 ≤ z ≤ 1.4. We constructed an ensemble cluster by stacking 581 spectroscopically identified cluster members with stellar mass M ⋆ ≥ 10 9.5 M ⊙ . We used the MAMPOSSt method to constrain several M ( r ) and β ( r ) models, and we then inverted the Jeans equation to determine the ensemble cluster β ( r ) in a non-parametric way. Finally, we combined the results of the M ( r ) and β ( r ) analysis to determine Q ( r ) for the ensemble cluster. Results. The concentration c 200 of the ensemble cluster mass profile is in excellent agreement with predictions from Λ cold dark matter (ΛCDM) cosmological numerical simulations, and with previous determinations for clusters of similar mass and at similar redshifts, obtained from gravitational lensing and X-ray data. We see no significant difference between the total mass density and either the galaxy number density distributions or the stellar mass distribution. Star-forming galaxies are spatially significantly less concentrated than quiescent galaxies. The orbits of cluster galaxies are isotropic near the center and more radial outside. Star-forming galaxies and galaxies of low stellar mass tend to move on more radially elongated orbits than quiescent galaxies and galaxies of high stellar mass. The profile Q ( r ), determined using either the total mass or the number density profile, is very close to the power-law behavior predicted by numerical simulations. Conclusions. The internal dynamics of clusters at the highest redshift probed in detail to date are very similar to those of lower-redshift clusters, and in excellent agreement with predictions of numerical simulations. The clusters in our s le have already reached a high degree of dynamical relaxation.
Publisher: EDP Sciences
Date: 27-10-2009
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201731880
Abstract: We present the version of the point source catalogue of the XXL Survey that was used, in part, in the first series of XXL papers. In this paper we release, in our database in Milan and at CDS: (i) the X-ray source catalogue with 26 056 objects in two areas of 25 deg 2 with a flux limit (at 3 σ ) of ~10 −15 erg s −1 cm −2 in [0.5–2] keV, and ~ 3 × 10 −15 erg s −1 cm −2 in [2–10] keV, yielding a 90% completeness limit of 5.8 × 10 −15 and 3.8 × 10 −14 respectively (ii) the associated multiwavelength catalogues with candidate counterparts of the X-ray sources in the infrared, near-infrared, optical, and ultraviolet (plus spectroscopic redshift when available) and (iii) a catalogue of spectroscopic redshifts recently obtained in the southern XXL area. We also present the basic properties of the X-ray point sources and their counterparts. Other catalogues described in the second series of XXL papers will be released contextually, and will constitute the second XXLdata release.
Publisher: American Astronomical Society
Date: 10-03-2008
Publisher: Oxford University Press (OUP)
Date: 23-06-2018
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201730789
Abstract: Modern cosmological simulations heavily rely on feedback from active galactic nuclei (AGN) in order to stave off overcooling in massive galaxies, and galaxy groups and clusters. Given that AGN are a key component of such simulations, an important independent test is whether or not the simulations capture the broad demographics of the observed AGN population. However, to date, comparisons between observed and simulated AGN populations have been relatively limited. Here, we have used the cosmo-OWLS suite of cosmological hydrodynamical simulations to produce realistic synthetic catalogs of X-ray AGN out to z = 3, with the aim of comparing the catalogs to the observed X-ray AGN population in the XXL survey and other recent surveys. We focused on the unabsorbed X-ray luminosity function (XLF), the Eddington ratio distribution, the black hole mass function, and the projected clustering of X-ray AGN. To compute the unabsorbed XLF of the simulated AGN, we used recent empirically-determined (luminosity-dependent) bolometric corrections, in order to convert the simulated bolometric luminosity into an observable X-ray luminosity. We show that, using these corrections, the simulated AGN s le accurately reproduces the observed XLF over 3 orders of magnitude in X-ray luminosity in all redshift bins from z = 0 out to z = 3. To compare to the observed Eddington ratio distribution and the clustering of AGN, we produced detailed “ XMM-Newton -detected” catalogs of the simulated AGN. This requires the production of synthetic X-ray images extracted from light cones of the simulations, which self-consistently contain both the X-ray AGN and the emission from diffuse, hot gas within galaxies, galaxy groups, and clusters and that fold in the relevant instrumental effects of XMM-Newton . We apply a luminosity- and redshift-dependent obscuration function for the AGN and employ the same AGN detection algorithm as used for the real XXL survey. We demonstrate that the detected population of simulated AGN reproduces the observed Eddington ratio distribution and projected clustering from XXL quite well. Based on these comparisons, we conclude that the simulations have a broadly realistic population of AGN and that our synthetic X-ray AGN catalogs should be useful for interpreting additional trends (e.g. environmental dependencies) and as a helpful tool for quantifying AGN contamination in galaxy group and cluster X-ray surveys.
Publisher: American Astronomical Society
Date: 24-09-2009
Publisher: Elsevier BV
Date: 04-2002
Publisher: SPIE
Date: 14-06-2006
DOI: 10.1117/12.671221
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201833238
Abstract: Context. Galaxy clusters trace the highest density peaks in the large-scale structure of the Universe. Their clustering provides a powerful probe that can be exploited in combination with cluster mass measurements to strengthen the cosmological constraints provided by cluster number counts. Aims. We investigate the spatial properties of a homogeneous s le of X-ray selected galaxy clusters from the XXL survey, the largest programme carried out by the XMM-Newton satellite. The measurements are compared to Λ-cold dark matter predictions, and used in combination with self-calibrated mass scaling relations to constrain the effective bias of the s le, b eff , and the matter density contrast, Ω M . Methods. We measured the angle-averaged two-point correlation function of the XXL cluster s le. The analysed catalogue consists of 182 X-ray selected clusters from the XXL second data release, with median redshift ⟨ z ⟩ = 0.317 and median mass ⟨ M 500 ⟩≃ 1.3 × 10 14 M ⊙ . A Markov chain Monte Carlo analysis is performed to extract cosmological constraints using a likelihood function constructed to be independent of the cluster selection function. Results. Modelling the redshift-space clustering in the scale range 10 r [ h −1 Mpc] 40, we obtain Ω M = 0.27 −0.04 +0.06 and b eff = 2.73 −0.20 +0.18 . This is the first time the two-point correlation function of an X-ray selected cluster catalogue at such relatively high redshifts and low masses has been measured. The XXL cluster clustering appears fully consistent with standard cosmological predictions. The analysis presented in this work demonstrates the feasibility of a cosmological exploitation of the XXL cluster clustering, paving the way for a combined analysis of XXL cluster number counts and clustering.
Publisher: Cambridge University Press (CUP)
Date: 11-2010
DOI: 10.1017/S1743921310010574
Abstract: We present results of a project aimed at establishing a set of 12 spectro-photometric standards over a wide wavelength range from 320 to 2500 nm. Currently no such set of standard stars covering the near-IR is available. Our strategy is to extend the useful range of existing well-established optical flux standards (Oke 1990, Hamuy et al . 1992, 1994) into the near-IR by means of integral field spectroscopy with SINFONI at the VLT combined with state-of-the-art white dwarf stellar atmospheric models (TMAP, Holberg et al . 2008). As a solid reference, we use two primary HST standard white dwarfs GD71 and GD153 and one HST secondary standard BD+17 4708. The data were collected through an ESO “Observatory Programme” over ~40 nights between February 2007 and September 2008.
Publisher: American Astronomical Society
Date: 24-07-2006
DOI: 10.1086/505532
Publisher: Elsevier BV
Date: 09-2013
Publisher: American Astronomical Society
Date: 03-2021
Abstract: We present ALMA CO (2-1) detections of 24 star-forming brightest cluster galaxies (BCGs) over 0.2 z 1.2, constituting the largest and most distant s le of molecular gas measurements in BCGs to date. The BCGs are selected from the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) to be IR-bright and therefore star-forming. We find that molecular gas is common in star-forming BCGs, detecting CO at a detection rate of 80% in our target s le of 30 objects. We additionally provide measurements of the star formation rate and stellar mass, calculated from existing MIPS 24 μ m and IRAC 3.6 μ m fluxes, respectively. We find these galaxies have molecular gas masses of 0.7–11.0 × 10 10 M ⊙ , comparable to other BCGs in this redshift range, and specific star formation rates that trace the main sequence of Elbaz et al. We compare our BCGs to those of the lower-redshift, cooling-flow BCG s le assembled by Edge and find that at z ≲ 0.6 the two s les show very similar correlations between their gas masses and specific SFRs. We suggest that, in this redshift regime, the ∼10% of BCGs that are star-forming process accreted molecular gas into stars through means that are agnostic to both their redshift and their cluster mass.
Publisher: American Astronomical Society
Date: 28-12-2011
Publisher: Oxford University Press (OUP)
Date: 21-04-2003
Publisher: EDP Sciences
Date: 15-09-2009
Publisher: American Astronomical Society
Date: 12-07-2017
Publisher: Oxford University Press (OUP)
Date: 23-03-2015
DOI: 10.1093/MNRAS/STV174
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We present the second public data release (DR2) from the DECam Local Volume Exploration survey (DELVE). DELVE DR2 combines new DECam observations with archival DECam data from the Dark Energy Survey, the DECam Legacy Survey, and other DECam community programs. DELVE DR2 consists of ∼160,000 exposures that cover ,000 deg 2 of the high-Galactic-latitude (∣ b ∣ 10°) sky in four broadband optical/near-infrared filters ( g , r , i , z ). DELVE DR2 provides point-source and automatic aperture photometry for ∼2.5 billion astronomical sources with a median 5 σ point-source depth of g = 24.3, r = 23.9, i = 23.5, and z = 22.8 mag. A region of ∼17,000 deg 2 has been imaged in all four filters, providing four-band photometric measurements for ∼618 million astronomical sources. DELVE DR2 covers more than 4 times the area of the previous DELVE data release and contains roughly 5 times as many astronomical objects. DELVE DR2 is publicly available via the NOIRLab Astro Data Lab science platform.
Publisher: Oxford University Press (OUP)
Date: 12-11-2020
Publisher: EDP Sciences
Date: 06-2020
DOI: 10.1051/0004-6361/202037754
Abstract: We study the stellar mass functions (SMFs) of star-forming and quiescent galaxies in 11 galaxy clusters at 1.0 z 1.4 drawn from the Gemini Observations of Galaxies in Rich Early ENvironments (GOGREEN) survey. Based on more than 500 h of Gemini/GMOS spectroscopy and deep multi-band photometry taken with a range of observatories, we probe the SMFs down to a stellar mass limit of 10 9.7 M ⊙ (10 9.5 M ⊙ for star-forming galaxies). At this early epoch, the fraction of quiescent galaxies is already highly elevated in the clusters compared to the field at the same redshift. The quenched fraction excess (QFE) represents the fraction of galaxies that would be star-forming in the field but are quenched due to their environment. The QFE is strongly mass dependent, and increases from ∼30% at M ⋆ = 10 9.7 M ⊙ to ∼80% at M ⋆ = 10 11.0 M ⊙ . Nonetheless, the shapes of the SMFs of the two in idual galaxy types, star-forming and quiescent galaxies, are identical between cluster and field to high statistical precision. Nevertheless, along with the different quiescent fractions, the total galaxy SMF is also environmentally dependent, with a relative deficit of low-mass galaxies in the clusters. These results are in stark contrast with findings in the local Universe, and therefore require a substantially different quenching mode to operate at early times. We discuss these results in light of several popular quenching models.
Publisher: EDP Sciences
Date: 14-08-2013
Publisher: Oxford University Press (OUP)
Date: 26-05-2021
Abstract: The analysis of current and future cosmological surveys of Type Ia supernovae (SNe Ia) at high redshift depends on the accurate photometric classification of the SN events detected. Generating realistic simulations of photometric SN surveys constitutes an essential step for training and testing photometric classification algorithms, and for correcting biases introduced by selection effects and contamination arising from core-collapse SNe in the photometric SN Ia s les. We use published SN time-series spectrophotometric templates, rates, luminosity functions, and empirical relationships between SNe and their host galaxies to construct a framework for simulating photometric SN surveys. We present this framework in the context of the Dark Energy Survey (DES) 5-yr photometric SN s le, comparing our simulations of DES with the observed DES transient populations. We demonstrate excellent agreement in many distributions, including Hubble residuals, between our simulations and data. We estimate the core collapse fraction expected in the DES SN s le after selection requirements are applied and before photometric classification. After testing different modelling choices and astrophysical assumptions underlying our simulation, we find that the predicted contamination varies from 7.2 to 11.7 per cent, with an average of 8.8 per cent and an r.m.s. of 1.1 per cent. Our simulations are the first to reproduce the observed photometric SN and host galaxy properties in high-redshift surveys without fine-tuning the input parameters. The simulation methods presented here will be a critical component of the cosmology analysis of the DES photometric SN Ia s le: correcting for biases arising from contamination, and evaluating the associated systematic uncertainty.
Publisher: Oxford University Press (OUP)
Date: 13-04-2020
Abstract: We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by the Dark Energy Survey Supernova Program (DES-SN) and used in the first DES-SN cosmological analysis. For the DES-SN s le, when considering a 5D (z, x1, c, α, β) bias correction, we find evidence of a Hubble residual ‘mass step’, where SNe Ia in high-mass galaxies (& M⊙) are intrinsically more luminous (after correction) than their low-mass counterparts by $\\gamma =0.040\\pm 0.019$ mag. This value is larger by 0.031 mag than the value found in the first DES-SN cosmological analysis. This difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. When using a 1D (redshift-only) bias correction the inferred mass step is larger, with $\\gamma =0.066\\pm 0.020$ mag. The 1D−5D γ difference for DES-SN is $0.026\\pm 0.009$ mag. We show that this difference is due to a strong correlation between host galaxy stellar mass and the x1 component of the 5D distance-bias correction. Including an intrinsic correlation between the observed properties of SNe Ia, stretch and colour, and stellar mass in simulated SN Ia s les, we show that a 5D fit recovers γ with −9 mmag bias compared to a +2 mmag bias for a 1D fit. This difference can explain part of the discrepancy seen in the data. Improvements in modelling correlations between galaxy properties and SN is necessary to ensure unbiased precision estimates of the dark energy equation of state as we enter the era of LSST.
Publisher: American Astronomical Society
Date: 07-1998
DOI: 10.1086/311450
Publisher: EDP Sciences
Date: 15-06-2016
Publisher: Oxford University Press (OUP)
Date: 17-05-2023
Abstract: We use the latest parallaxes measurements from Gaia DR3 to obtain a geometric calibration of the tip of the red giant branch (TRGB) in Cousins I magnitudes as a standard candle for cosmology. We utilize the following surveys: SkyMapper DR3, APASS DR9, ATLAS Refcat2, and Gaia DR3 synthetic photometry to obtain multiple zero-point calibrations of the TRGB magnitude, $M_{I}^{TRGB}$. Our s le contains Milky Way halo stars at high galactic latitudes (|b| & 36) where the impact of metallicity, dust, and crowding are minimized. The magnitude of the TRGB is identified using Sobel edge detection, but this approach introduced a systematic offset. To address this issue, we utilized simulations with parsec isochrones and showed how to calibrate and remove this bias. Applying our method within the colour range where the slope of the TRGB is relatively flat for metal-poor halo stars (1.55 & (BP − RP) & 2.25), we find a weighted average $M_{I}^{TRGB} = -4.042 \pm 0.041$ (stat) ±0.031 (sys) mag. A geometric calibration of the Milky Way TRGB has the benefit of being independent of other distance indicators and will help probe systematics in the local distance ladder, leading to improved measurements of the Hubble constant.
Publisher: American Astronomical Society
Date: 11-01-2011
Publisher: Oxford University Press (OUP)
Date: 24-05-2021
Abstract: We present DES14X2fna, a high-luminosity, fast-declining Type IIb supernova (SN IIb) at redshift z = 0.0453, detected by the Dark Energy Survey (DES). DES14X2fna is an unusual member of its class, with a light curve showing a broad, luminous peak reaching Mr ≃ −19.3 mag 20 d after explosion. This object does not show a linear decline tail in the light curve until ≃60 d after explosion, after which it declines very rapidly (4.30 ± 0.10 mag 100 d−1 in the r band). By fitting semi-analytic models to the photometry of DES14X2fna, we find that its light curve cannot be explained by a standard 56Ni decay model as this is unable to fit the peak and fast tail decline observed. Inclusion of either interaction with surrounding circumstellar material or a rapidly-rotating neutron star (magnetar) significantly increases the quality of the model fit. We also investigate the possibility for an object similar to DES14X2fna to act as a contaminant in photometric s les of SNe Ia for cosmology, finding that a similar simulated object is misclassified by a recurrent neural network (RNN)-based photometric classifier as an SN Ia in ∼1.1–2.4 per cent of cases in DES, depending on the probability threshold used for a positive classification.
Publisher: American Astronomical Society
Date: 28-12-2011
Publisher: Oxford University Press (OUP)
Date: 29-06-2020
Abstract: We consider the effects of weak gravitational lensing on observations of 196 spectroscopically confirmed Type Ia Supernovae (SNe Ia) from years 1 to 3 of the Dark Energy Survey (DES). We simultaneously measure both the angular correlation function and the non-Gaussian skewness caused by weak lensing. This approach has the advantage of being insensitive to the intrinsic dispersion of SNe Ia magnitudes. We model the litude of both effects as a function of σ8, and find σ8 =1.2$^{+0.9}_{-0.8}$. We also apply our method to a subs le of 488 SNe from the Joint Light-curve Analysis (JLA chosen to match the redshift range we use for this work), and find σ8 =0.8$^{+1.1}_{-0.7}$. The comparable uncertainty in σ8 between DES–SN and the larger number of SNe from JLA highlights the benefits of homogeneity of the DES–SN s le, and improvements in the calibration and data analysis.
Publisher: American Astronomical Society
Date: 28-12-2011
Publisher: EDP Sciences
Date: 2006
DOI: 10.1051/EAS:2006062
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2008
Publisher: EDP Sciences
Date: 12-2017
DOI: 10.1051/0004-6361/201731267
Abstract: Context. Measuring and calibrating relations between cluster observables is critical for resource-limited studies. The mass–richness relation of clusters offers an observationally inexpensive way of estimating masses. Its calibration is essential for cluster and cosmological studies, especially for high-redshift clusters. Weak gravitational lensing magnification is a promising and complementary method to shear studies, that can be applied at higher redshifts. Aims. We aim to employ the weak lensing magnification method to calibrate the mass–richness relation up to a redshift of 1.4. We used the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) galaxy cluster candidates (0.2 z 1.4) and optical data from the Canada France Hawaii Telescope (CFHT) to test whether magnification can be effectively used to constrain the mass of high-redshift clusters. Methods. Lyman-break galaxies (LBGs) selected using the u -band dropout technique and their colours were used as a background s le of sources. LBG positions were cross-correlated with the centres of the s le of SpARCS clusters to estimate the magnification signal, which was optimally-weighted using an externally-calibrated LBG luminosity function. The signal was measured for cluster sub-s les, binned in both redshift and richness. Results. We measured the cross-correlation between the positions of galaxy cluster candidates and LBGs and detected a weak lensing magnification signal for all bins at a detection significance of 2.6–5.5 σ . In particular, the significance of the measurement for clusters with z 1.0 is 4.1 σ for the entire cluster s le we obtained an average M 200 of 1.28 -0.21 +0.23 × 10 14 M ⊙ . Conclusions. Our measurements demonstrated the feasibility of using weak lensing magnification as a viable tool for determining the average halo masses for s les of high redshift galaxy clusters. The results also established the success of using galaxy over-densities to select massive clusters at z 1. Additional studies are necessary for further modelling of the various systematic effects we discussed.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2014
Publisher: American Astronomical Society
Date: 12-07-2012
Publisher: No publisher found
Date: 2001
Publisher: Oxford University Press (OUP)
Date: 03-06-2017
Publisher: American Physical Society (APS)
Date: 07-07-2020
Publisher: EDP Sciences
Date: 19-11-2010
Publisher: Oxford University Press (OUP)
Date: 24-02-2021
Abstract: Beyond ΛCDM, physics or systematic errors may cause subsets of a cosmological data set to appear inconsistent when analysed assuming ΛCDM. We present an application of internal consistency tests to measurements from the Dark Energy Survey Year 1 (DES Y1) joint probes analysis. Our analysis relies on computing the posterior predictive distribution (PPD) for these data under the assumption of ΛCDM. We find that the DES Y1 data have an acceptable goodness of fit to ΛCDM, with a probability of finding a worse fit by random chance of p = 0.046. Using numerical PPD tests, supplemented by graphical checks, we show that most of the data vector appears completely consistent with expectations, although we observe a small tension between large- and small-scale measurements. A small part (roughly 1.5 per cent) of the data vector shows an unusually large departure from expectations excluding this part of the data has negligible impact on cosmological constraints, but does significantly improve the p-value to 0.10. The methodology developed here will be applied to test the consistency of DES Year 3 joint probes data sets.
Publisher: American Astronomical Society
Date: 18-11-2020
Publisher: American Astronomical Society
Date: 12-2005
DOI: 10.1086/497635
Publisher: No publisher found
Date: 2001
DOI: 10.1007/10854354\_50
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201834022
Abstract: Context. We present an estimation of cosmological parameters with clusters of galaxies. Aims. We constrain the Ω m , σ 8 , and w parameters from a stand-alone s le of X-ray clusters detected in the 50 deg 2 XMM-XXL survey with a well-defined selection function. Methods. We analyse the redshift distribution of a s le comprising 178 high signal-to-noise ratio clusters out to a redshift of unity. The cluster s le scaling relations are determined in a self-consistent manner. Results. In a lambda cold dark matter (ΛCDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the Planck Sunyaev-Zel’dovich clusters for a totally different s le (mass/redshift range, selection biases, and scaling relations). However, with this preliminary s le and current mass calibration uncertainty, we find no inconsistency with the Planck CMB cosmology. If we relax the w parameter, the Planck CMB uncertainties increase by a factor of ~10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on Ω m = 0.316 ± 0.060, σ 8 = 0.814 ± 0.054, and w = −1.02 ± 0.20. Conclusions. This first self-consistent cosmological analysis of a s le of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger s le extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3.
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B304072K
Publisher: American Astronomical Society
Date: 03-08-2011
Publisher: Oxford University Press (OUP)
Date: 07-1999
Publisher: American Astronomical Society
Date: 20-09-1999
DOI: 10.1086/307740
Publisher: Oxford University Press (OUP)
Date: 30-09-2020
Abstract: We present the first public data release of the GOGREEN (Gemini Observations of Galaxies in Rich Early Environments) and GCLASS (Gemini CLuster Astrophysics Spectroscopic Survey) surveys of galaxies in dense environments, spanning a redshift range 0.8 & z & 1.5. The surveys consist of deep, multiwavelength photometry and extensive Gemini GMOS spectroscopy of galaxies in 26 overdense systems ranging in halo mass from small groups to the most massive clusters. The objective of both projects was primarily to understand how the evolution of galaxies is affected by their environment, and to determine the physical processes that lead to the quenching of star formation. There was an emphasis on obtaining unbiased spectroscopy over a wide stellar mass range (M ≳ 2 × 1010 M⊙), throughout and beyond the cluster virialized regions. The final spectroscopic s le includes 2771 unique objects, of which 2257 have reliable spectroscopic redshifts. Of these, 1704 have redshifts in the range 0.8 & z & 1.5, and nearly 800 are confirmed cluster members. Imaging spans the full optical and near-infrared wavelength range, at depths comparable to the UltraVISTA survey, and includes Hubble Space Telescope/Wide Field Camera 3 F160W (GOGREEN) and F140W (GCLASS). This data release includes fully reduced images and spectra, with catalogues of advanced data products including redshifts, line strengths, star formation rates, stellar masses, and rest-frame colours. Here, we present an overview of the data, including an analysis of the spectroscopic completeness and redshift quality.
Publisher: EDP Sciences
Date: 2003
Publisher: American Astronomical Society
Date: 25-02-2016
Publisher: Oxford University Press (OUP)
Date: 21-12-2020
Abstract: Analyses of Type Ia supernovae (SNe Ia) have found puzzling correlations between their standardized luminosities and host galaxy properties: SNe Ia in high-mass, passive hosts appear brighter than those in lower mass, star-forming hosts. We examine the host galaxies of SNe Ia in the Dark Energy Survey 3-yr spectroscopically confirmed cosmological s le, obtaining photometry in a series of ‘local’ apertures centred on the SN, and for the global host galaxy. We study the differences in these host galaxy properties, such as stellar mass and rest-frame U − R colours, and their correlations with SN Ia parameters including Hubble residuals. We find all Hubble residual steps to be & σ in significance, both for splitting at the traditional environmental property s le median and for the step of maximum significance. For stellar mass, we find a maximal local step of 0.098 ± 0.018 mag ∼0.03 mag greater than the largest global stellar mass step in our s le (0.070 ± 0.017 mag). When splitting at the s le median, differences between local and global U − R steps are small, both ∼0.08 mag, but are more significant than the global stellar mass step (0.057 ± 0.017 mag). We split the data into sub-s les based on SN Ia light-curve parameters: stretch (x1) and colour (c), finding that redder objects (c & 0) have larger Hubble residual steps, for both stellar mass and U − R, for both local and global measurements, of ∼0.14 mag. Additionally, the bluer (star-forming) local environments host a more homogeneous SN Ia s le, with local U − R rms scatter as low as 0.084 ± 0.017 mag for blue (c & 0) SNe Ia in locally blue U − R environments.
Publisher: Oxford University Press (OUP)
Date: 20-06-2022
Abstract: As part of the cosmology analysis using Type Ia Supernovae (SN Ia) in the Dark Energy Survey (DES), we present photometrically identified SN Ia s les using multiband light curves and host galaxy redshifts. For this analysis, we use the photometric classification framework SuperNNovatrained on realistic DES-like simulations. For reliable classification, we process the DES SN programme (DES-SN) data and introduce improvements to the classifier architecture, obtaining classification accuracies of more than 98 per cent on simulations. This is the first SN classification to make use of ensemble methods, resulting in more robust s les. Using photometry, host galaxy redshifts, and a classification probability requirement, we identify 1863 SNe Ia from which we select 1484 cosmology-grade SNe Ia spanning the redshift range of 0.07 & z & 1.14. We find good agreement between the light-curve properties of the photometrically selected s le and simulations. Additionally, we create similar SN Ia s les using two types of Bayesian Neural Network classifiers that provide uncertainties on the classification probabilities. We test the feasibility of using these uncertainties as indicators for out-of-distribution candidates and model confidence. Finally, we discuss the implications of photometric s les and classification methods for future surveys such as Vera C. Rubin Observatory Legacy Survey of Space and Time.
Publisher: Oxford University Press (OUP)
Date: 26-09-2020
Abstract: Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our s le has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5M⊙) at high redshift for the first time. We find five candidates with significant (at & .74% single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3× 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 years (i.e., 1–2 years in rest frame) having ∼4–6 cycles spanned by the observations. If all five candidates are periodically variable quasars, this translates into a detection rate of ${\\sim }0.8^{+0.5}_{-0.3}$% or ${\\sim }1.1^{+0.7}_{-0.5}$ quasar per deg2. Our detection rate is 4–80 times larger than those found by previous searches using shallower surveys over larger areas. This discrepancy is likely caused by differences in the quasar populations probed and the survey data qualities. We discuss implications on the future direct detection of low-frequency gravitational waves. Continued photometric monitoring will further assess the robustness and characteristics of these candidate periodic quasars to determine their physical origins.
Publisher: Emerald
Date: 04-11-2019
DOI: 10.1108/EEMCS-05-2019-0107
Abstract: The learning outcomes are as follows: understanding online, traditional and omnichannel retail and the challenges and benefits of each method evaluating the effect of consumer buying behaviour on a company’s growth strategy assessing the effect of changing industry dynamics and technology on consumer behaviour and understanding the role of consistent customer experience across different retail mediums. This case looks at Yuppiechef, a successful e-commerce business, and their move from “clicks to bricks” with the introduction of retail stores. Founder and CEO of Yuppiechef, Andrew Smith, shares the current business status and considers how to maintain the brand’s culture with the growth of retail and being an omnichannel pioneer. The primary target audience for this teaching case is postgraduate business students, especially students of digital marketing, strategy and e-commerce. This teaching case is intended to be used as case study in postgraduate business programmes such as Master of Business Administration (MBA), a specialist masters’ programme such as MM (Entrepreneurship), post-graduate diploma in management (PGDip), as well as selected executive education programmes. Teaching Notes are available for educators only. CSS 8: Marketing.
Publisher: Oxford University Press (OUP)
Date: 11-2012
Publisher: American Astronomical Society
Date: 10-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B512263E
Publisher: American Chemical Society (ACS)
Date: 29-10-2005
DOI: 10.1021/JM040208L
Abstract: Dynamin I is a GTPase enzyme required for endocytosis and is an excellent target for the design of potential endocytosis inhibitors. Screening of a library of tyrphostins, in our laboratory, against the GTPase activity of dynamin I gave rise to a microM potent lead, 2-cyano-3-(3,4-dihydroxyphenyl)thioacrylamide (1, IC50 70 microM). Our initial investigations suggested that only the dimeric form of 1 displayed dynamin I GTPase inhibitory activity. Subsequent synthetic iterations were based on dimeric analogues and afforded a number of small molecules, low microM potent, inhibitors of dynamin I GTPase, in particular, symmetrical analogues with a minimum of two free phenolic -OHs: catechol-acrylamide (9) (IC50= 5.1 +/- 0.6 microM), its 3,4,5-trihydroxy congener (10) (IC50= 1.7 +/- 0.2 microM), and the corresponding 3-methyl ether (11) (IC50= 9 +/- 3 microM). Increasing the length of the central alkyl spacer from ethyl to propyl (22-24) afforded essentially identical activity with IC50's of 1.7 +/- 0.2, 1.7 +/- 0.2, and 5 +/- 1 microM, respectively. No decrease in activity was noted until the introduction of a hexyl spacer. Our studies highlight the requirement for two free amido NHs with neither the mono-N-methyl (86) nor the bis-N-methyl (87) analogues inhibiting dynamin I GTPase. A similar effect was noted for the removal of the nitrile moieties. However, modest potency was observed with the corresponding ester analogues of 9-11: ethyl ester (90), propyl ester (91), and butyl ester (92), with IC50's of 42 +/- 3, 38 +/- 2, and 61 +/- 2 microM, respectively. Our studies reveal the most potent and promising dynamin I GTPase inhibitor in this series as (22), which is also known as BisT.
Publisher: American Astronomical Society
Date: 20-06-2017
Publisher: EDP Sciences
Date: 02-2002
Publisher: EDP Sciences
Date: 10-2016
Publisher: American Astronomical Society
Date: 2023
Abstract: Gravitationally lensed supernovae (LSNe) are important probes of cosmic expansion, but they remain rare and difficult to find. Current cosmic surveys likely contain 5–10 LSNe in total while next-generation experiments are expected to contain several hundred to a few thousand of these systems. We search for these systems in observed Dark Energy Survey (DES) five year SN fields—10 3 sq. deg. regions of sky imaged in the griz bands approximately every six nights over five years. To perform the search, we utilize the DeepZipper approach: a multi-branch deep learning architecture trained on image-level simulations of LSNe that simultaneously learns spatial and temporal relationships from time series of images. We find that our method obtains an LSN recall of 61.13% and a false-positive rate of 0.02% on the DES SN field data. DeepZipper selected 2245 candidates from a magnitude-limited ( m i 22.5) catalog of 3,459,186 systems. We employ human visual inspection to review systems selected by the network and find three candidate LSNe in the DES SN fields.
Publisher: Wiley
Date: 12-2005
Publisher: American Astronomical Society
Date: 12-1996
DOI: 10.1086/118195
Publisher: Oxford University Press (OUP)
Date: 04-06-2013
DOI: 10.1093/MNRAS/STT777
Publisher: EDP Sciences
Date: 04-2002
Publisher: American Astronomical Society
Date: 05-03-2020
Publisher: EDP Sciences
Date: 10-2008
Publisher: Oxford University Press (OUP)
Date: 29-07-2015
Publisher: American Astronomical Society
Date: 02-04-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B710014K
Abstract: Ionic liquids comprised of tetradecyltrihexyl- and tetrabutyl-phosphonium cations paired with chloride or sulfonyl amide anions exhibit properties that reflect strong ion association, including comparatively low viscosity as well as a degree of volatility, and hence exemplify an interesting intermediate state between true ionic and true molecular liquids.
Publisher: American Astronomical Society
Date: 21-02-2019
Publisher: EDP Sciences
Date: 11-06-2004
Publisher: Oxford University Press (OUP)
Date: 13-06-2017
Publisher: SPIE
Date: 12-07-2008
DOI: 10.1117/12.789395
Publisher: American Astronomical Society
Date: 12-10-2011
Publisher: Oxford University Press (OUP)
Date: 11-01-2023
Abstract: We present the luminosity functions and host galaxy properties of the Dark Energy Survey (DES) core-collapse supernova (CCSN) s le, consisting of 69 Type II and 50 Type Ibc spectroscopically and photometrically confirmed supernovae over a redshift range 0.045 & z & 0.25. We fit the observed DES griz CCSN light curves and K-correct to produce rest-frame R-band light curves. We compare the s le with lower redshift CCSN s les from Zwicky Transient Facility (ZTF) and Lick Observatory Supernova Search (LOSS). Comparing luminosity functions, the DES and ZTF s les of SNe II are brighter than that of LOSS with significances of 3.0σ and 2.5σ, respectively. While this difference could be caused by redshift evolution in the luminosity function, simpler explanations such as differing levels of host extinction remain a possibility. We find that the host galaxies of SNe II in DES are on average bluer than in ZTF, despite having consistent stellar mass distributions. We consider a number of possibilities to explain this – including galaxy evolution with redshift, selection biases in either the DES or ZTF s les, and systematic differences due to the different photometric bands available – but find that none can easily reconcile the differences in host colour between the two s les and thus its cause remains uncertain.
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201732379
Abstract: The classification of the host galaxies of the radio sources in the 25 deg 2 ultimate XMM extragalactic survey south field (XXL-S) is presented. XXL-S was surveyed at 2.1 GHz with the Australia Telescope Compact Array (ATCA) and is thus far the largest area radio survey conducted down to rms flux densities of σ ~ 41 μ Jy beam −1 . Of the 6287 radio sources in XXL-S, 4758 (75.7%) were cross-matched to an optical counterpart using the likelihood ratio technique. There are 1110 spectroscopic redshifts and 3648 photometric redshifts available for the counterparts, of which 99.4% exist out to z ~ 4. A number of multiwavelength diagnostics, including X-ray luminosities, mid-infrared colours, spectral energy distribution fits, radio luminosities, and optical emission lines and colours, were used to classify the sources into three types: low-excitation radio galaxies (LERGs), high-excitation radio galaxies (HERGs), and star-forming galaxies (SFGs). The final s le contains 1729 LERGs (36.3%), 1159 radio-loud HERGs (24.4%), 296 radio-quiet HERGs (6.2%), 558 SFGs (11.7%), and 1016 unclassified sources (21.4%). The XXL-S sub-mJy radio source population is composed of ~75% active galactic nuclei and ~20% SFGs down to 0.2 mJy. The host galaxy properties of the HERGs in XXL-S are independent of the HERG selection, but the XXL-S LERG and SFG selection is, due to the low spectral coverage, largely determined by the known properties of those populations. Considering this caveat, the LERGs tend to exist in the most massive galaxies with low star formation rates and redder colours, whereas the HERGs and SFGs exist in galaxies of lower mass, higher star formation rates, and bluer colours. The fraction of blue host galaxies is higher for radio-quiet HERGs than for radio-loud HERGs. LERGs and radio-loud HERGs are found at all radio luminosities, but radio-loud HERGs tend to be more radio luminous than LERGs at a given redshift. These results are consistent with the emerging picture in which LERGs exist in the most massive quiescent galaxies typically found in clusters with hot X-ray halos and HERGs are associated with ongoing star formation in their host galaxies via the accretion of cold gas.
Publisher: American Astronomical Society
Date: 12-2007
DOI: 10.1086/522827
Publisher: Oxford University Press (OUP)
Date: 04-03-2020
Abstract: We present results on the environmental dependence of the star-forming galaxy main sequence in 11 galaxy cluster fields at 1.0 & z & 1.5 from the Gemini Observations of Galaxies in Rich Early Environments Survey (GOGREEN) survey. We use a homogeneously selected s le of field and cluster galaxies whose membership is derived from dynamical analysis. Using [$\\rm{O{\\small II}}$]-derived star formation rates (SFRs), we find that cluster galaxies have suppressed SFRs at fixed stellar mass in comparison to their field counterparts by a factor of 1.4 ± 0.1 (∼3.3σ) across the stellar mass range: 9.0 & log (M*/M⊙) & 11.2. We also find that this modest suppression in the cluster galaxy star-forming main sequence is mass and redshift dependent: the difference between cluster and field increases towards lower stellar masses and lower redshift. When comparing the distribution of cluster and field galaxy SFRs to the star-forming main sequence, we find an overall shift towards lower SFRs in the cluster population, and note the absence of a tail of high SFR galaxies as seen in the field. Given this observed suppression in the cluster galaxy star-forming main sequence, we explore the implications for several scenarios such as formation time differences between cluster and field galaxies, and environmentally induced star formation quenching and associated time-scales.
Publisher: EDP Sciences
Date: 19-04-2006
Publisher: SPIE
Date: 14-06-2006
DOI: 10.1117/12.672231
Publisher: American Astronomical Society
Date: 23-10-2018
Publisher: American Astronomical Society
Date: 11-2001
DOI: 10.1086/323214
Publisher: Cambridge University Press (CUP)
Date: 2013
Abstract: We use the wide-field capabilities of the 2 degree field fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first 3 years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ks per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our s le that hosted photometrically classified Type Ia supernovae (SNe Ia) is z ~ 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the 3-year s le of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4-m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of the sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.MEDENGPHY.2011.08.001
Abstract: Automated methods of neonatal EEG seizure detection attempt to highlight the evolving, stereotypical, pseudo-periodic, nature of EEG seizure while rejecting the nonstationary, modulated, coloured stochastic background in the presence of various EEG artefacts. An important aspect of neonatal seizure detection is, therefore, the accurate representation and detection of pseudo-periodicity in the neonatal EEG. This paper describes a method of detecting pseudo-periodic components associated with neonatal EEG seizure based on a novel signal representation the nonstationary frequency marginal (NFM). The NFM can be considered as an alternative time-frequency distribution (TFD) frequency marginal. This method integrates the TFD along data-dependent, time-frequency paths that are automatically extracted from the TFD using an edge linking procedure and has the advantage of reducing the dimension of a TFD. The reduction in dimension simplifies the process of estimating a decision statistic designed for the detection of the pseudo-periodicity associated with neonatal EEG seizure. The use of the NFM resulted in a significant detection improvement compared to existing stationary and nonstationary methods. The decision statistic estimated using the NFM was then combined with a measurement of EEG litude and nominal pre- and post-processing stages to form a seizure detection algorithm. This algorithm was tested on a neonatal EEG database of 18 neonates, 826 h in length with 1389 seizures, and achieved comparable performance to existing second generation algorithms (a median receiver operating characteristic area of 0.902 IQR 0.835-0.943 across 18 neonates).
Publisher: IEEE
Date: 08-2011
Publisher: EDP Sciences
Date: 2014
Publisher: American Astronomical Society
Date: 14-07-2009
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201731606
Abstract: Context. In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster s les is critical. Aims. The XXL Survey has been specifically designed to provide a well characterised s le of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups. Methods. Following from the publication of the hundred brightest XXL clusters, we now release a s le containing 365 clusters in total, down to a flux of a few 10 −15 erg s −1 cm −2 in the [0.5–2] keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster s le, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the [0.5–2] keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10 −15 erg s −1 cm −2 . Results. Our cluster s le extends from z ~ 0 to z ~ 1.2, with one cluster at z ~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a s le of 18 possible fossil groups. Conclusions. This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg 2 area out to z ~ 1.
Publisher: Elsevier BV
Date: 12-2005
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2017.2
Abstract: We compare two Type Ia supernova s les that are drawn from a spectroscopically confirmed Type Ia supernova s le: a host-selected s le in which SNe Ia are restricted to those that have a spectroscopic redshift from the host and a broader, more traditional s le in which the redshift could come from either the SN or the host. The host-selected s le is representative of SN s les that will use the redshift of the host to infer the SN redshift, long after the SN has faded from view. We find that SNe Ia that are selected on the availability of a redshift from the host differ from SNe Ia that are from the broader s le. The former tend to be redder, have narrower light curves, live in more massive hosts, and tend to be at lower redshifts. We find that constraints on the equation of state of dark energy, w , and the matter density, Ω M , remain consistent between these two types of s les. Our results are important for ongoing and future supernova surveys, which unlike previous supernova surveys, will have limited real-time follow-up to spectroscopically classify the SNe they discover. Most of the redshifts in these surveys will come from the hosts.
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/CH03221
Abstract: Ionic liquids based on the imidazolium cation are found to degrade, yielding volatile degradation products, at temperatures significantly lower than previously reported and thus a parameter Tz/x (the maximum operating temperature) is developed to provide a more appropriate estimate of thermal stability.
Publisher: EDP Sciences
Date: 30-05-2005
Publisher: Oxford University Press (OUP)
Date: 09-04-2019
DOI: 10.1093/MNRAS/STZ978
Abstract: We present an improved measurement of the Hubble constant (H0) using the ‘inverse distance ladder’ method, which adds the information from 207 Type Ia supernovae (SNe Ia) from the Dark Energy Survey (DES) at redshift 0.018 & z & 0.85 to existing distance measurements of 122 low-redshift (z & 0.07) SNe Ia (Low-z) and measurements of Baryon Acoustic Oscillations (BAOs). Whereas traditional measurements of H0 with SNe Ia use a distance ladder of parallax and Cepheid variable stars, the inverse distance ladder relies on absolute distance measurements from the BAOs to calibrate the intrinsic magnitude of the SNe Ia. We find H0 = 67.8 ± 1.3 km s−1 Mpc−1 (statistical and systematic uncertainties, 68 per cent confidence). Our measurement makes minimal assumptions about the underlying cosmological model, and our analysis was blinded to reduce confirmation bias. We examine possible systematic uncertainties and all are below the statistical uncertainties. Our H0 value is consistent with estimates derived from the Cosmic Microwave Background assuming a ΛCDM universe.
Publisher: Springer-Verlag
DOI: 10.1007/10828557_11
Publisher: American Astronomical Society
Date: 13-12-2010
Publisher: American Astronomical Society
Date: 10-09-1997
DOI: 10.1086/304567
Publisher: American Astronomical Society
Date: 30-04-2007
DOI: 10.1086/517492
Publisher: SPIE
Date: 16-09-2004
DOI: 10.1117/12.551147
Publisher: SPIE
Date: 25-10-2004
DOI: 10.1117/12.551148
Publisher: Oxford University Press (OUP)
Date: 27-06-2020
Abstract: Obtaining accurate distributions of galaxy redshifts is a critical aspect of weak lensing cosmology experiments. One of the methods used to estimate and validate redshift distributions is to apply weights to a spectroscopic s le, so that their weighted photometry distribution matches the target s le. In this work, we estimate the selection bias in redshift that is introduced in this procedure. We do so by simulating the process of assembling a spectroscopic s le (including observer-assigned confidence flags) and highlight the impacts of spectroscopic target selection and redshift failures. We use the first year (Y1) weak lensing analysis in Dark Energy Survey (DES) as an ex le data set but the implications generalize to all similar weak lensing surveys. We find that using colour cuts that are not available to the weak lensing galaxies can introduce biases of up to Δz ∼ 0.04 in the weighted mean redshift of different redshift intervals (Δz ∼ 0.015 in the case most relevant to DES). To assess the impact of incompleteness in spectroscopic s les, we select only objects with high observer-defined confidence flags and compare the weighted mean redshift with the true mean. We find that the mean redshift of the DES Y1 weak lensing s le is typically biased at the Δz = 0.005−0.05 level after the weighting is applied. The bias we uncover can have either sign, depending on the s les and redshift interval considered. For the highest redshift bin, the bias is larger than the uncertainties in the other DES Y1 redshift calibration methods, justifying the decision of not using this method for the redshift estimations. We discuss several methods to mitigate this bias.
Publisher: Oxford University Press (OUP)
Date: 02-03-2023
Publisher: American Astronomical Society
Date: 03-02-2016
Publisher: Oxford University Press (OUP)
Date: 08-07-2017
Publisher: American Astronomical Society
Date: 07-2004
DOI: 10.1086/421747
Publisher: IOP Publishing
Date: 05-12-2016
Publisher: American Astronomical Society
Date: 27-01-2012
Publisher: American Astronomical Society
Date: 06-1998
DOI: 10.1086/311376
Publisher: No publisher found
Date: 2008
Publisher: Oxford University Press (OUP)
Date: 20-10-2022
Abstract: We use stacked spectra of the host galaxies of photometrically identified Type Ia supernovae (SNe Ia) from the Dark Energy Survey (DES) to search for correlations between Hubble diagram residuals and the spectral properties of the host galaxies. Utilizing full spectrum fitting techniques on stacked spectra binned by Hubble residual, we find no evidence for trends between Hubble residuals and properties of the host galaxies that rely on spectral absorption features (& .3σ), such as stellar population age, metallicity, and mass-to-light ratio. However, we find significant trends between the Hubble residuals and the strengths of [O ii] (4.4σ) and the Balmer emission lines (3σ). These trends are weaker than the well-known trend between Hubble residuals and host galaxy stellar mass (7.2σ) that is derived from broad-band photometry. After light-curve corrections, we see fainter SNe Ia residing in galaxies with larger line strengths. We also find a trend (3σ) between Hubble residual and the Balmer decrement (a measure of reddening by dust) using H β and H γ. The trend, quantified by correlation coefficients, is slightly more significant in the redder SNe Ia, suggesting that the bluer SNe Ia are relatively unaffected by dust in the interstellar medium of the host and that dust contributes to current Hubble diagram scatter impacting the measurement of cosmological parameters.
Publisher: Oxford University Press (OUP)
Date: 06-2008
Publisher: Oxford University Press (OUP)
Date: 13-04-2020
Abstract: We present an analysis of DES17X1boj and DES16E2bjy, two peculiar transients discovered by the Dark Energy Survey (DES). They exhibit nearly identical double-peaked light curves that reach very different maximum luminosities (Mr = −15.4 and −17.9, respectively). The light-curve evolution of these events is highly atypical and has not been reported before. The transients are found in different host environments: DES17X1boj was found near the nucleus of a spiral galaxy, while DES16E2bjy is located in the outskirts of a passive red galaxy. Early photometric data are well fitted with a blackbody and the resulting moderate photospheric expansion velocities (1800 km s−1 for DES17X1boj and 4800 km s−1 for DES16E2bjy) suggest an explosive or eruptive origin. Additionally, a feature identified as high-velocity Ca ii absorption ($v$ ≈ 9400 km s−1) in the near-peak spectrum of DES17X1boj may imply that it is a supernova. While similar light-curve evolution suggests a similar physical origin for these two transients, we are not able to identify or characterize the progenitors.
Publisher: American Astronomical Society
Date: 05-2021
Abstract: The See Change survey was designed to make z 1 cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass measurements through weak lensing. This survey observed twelve galaxy clusters with the Hubble Space Telescope (HST) spanning the redshift range z = 1.13–1.75, discovering 57 likely transients and 27 likely SNe Ia at z ∼ 0.8–2.3. As in similar previous surveys, this proved to be a highly efficient use of HST for supernova observations the See Change survey additionally tested the feasibility of maintaining, or further increasing, the efficiency at yet higher redshifts, where we have less detailed information on the expected cluster masses and star formation rates. We find that the resulting number of SNe Ia per orbit is a factor of ∼8 higher than for a field search, and 45% of our orbits contained an active SN Ia within 22 rest-frame days of peak, with one of the clusters by itself yielding 6 of the SNe Ia. We present the survey design, pipeline, and supernova discoveries. Novel features include fully blinded supernova searches, the first random forest candidate classifier for unders led IR data (with a 50% detection threshold within 0.05 mag of human searchers), real-time forward-modeling photometry of candidates, and semi-automated photometric classifications and follow-up forecasts. We also describe the spectroscopic follow-up, instrumental in measuring host galaxy redshifts. The cosmology analysis of our s le will be presented in a companion paper.
Publisher: American Astronomical Society
Date: 27-07-2021
Publisher: Oxford University Press (OUP)
Date: 14-04-2021
Abstract: We present a revised Spectral Adaptive Light Curve Template (SALT2) surface (SALT2-2021) for fitting the light curves of Type Ia supernovae (SNe Ia), which incorporates new measurements of zero-point calibration offsets and Milky Way extinction. The most notable change in the new surface occurs in the UV region. This new surface alters the distance measurements of SNe Ia, which can be used to investigate the nature of dark energy by probing the expansion history of the Universe. Using the revised SALT2 surface on public data from the first 3 yr of the Dark Energy Survey Supernova Program (combined with an external low-z SNe Ia s le) and combining with cosmic microwave background constraints, we find a change in the dark energy equation-of-state parameter, Δw = 0.015 ± 0.004. This result highlights the continued importance of controlling and reducing systematic uncertainties, particularly with the next generation of supernova analyses aiming to improve constraints on dark energy properties.
Publisher: EDP Sciences
Date: 06-2001
Publisher: SPIE
Date: 14-06-2006
DOI: 10.1117/12.673901
Publisher: American Astronomical Society
Date: 20-10-2008
DOI: 10.1086/589937
Publisher: No publisher found
Date: 2005
DOI: 10.1007/10828557\_9
Publisher: EDP Sciences
Date: 07-2004
Publisher: Springer Berlin Heidelberg
Date: 11-11-2005
DOI: 10.1007/10828557_9
Publisher: Oxford University Press (OUP)
Date: 19-02-2014
DOI: 10.1093/MNRAS/STU135
Publisher: Oxford University Press (OUP)
Date: 09-04-2014
DOI: 10.1093/MNRAS/STU376
Publisher: Oxford University Press (OUP)
Date: 05-04-2018
DOI: 10.1093/MNRAS/STY859
Publisher: Oxford University Press (OUP)
Date: 21-04-2014
DOI: 10.1093/MNRAS/STU496
Publisher: American Astronomical Society
Date: 10-06-2020
Publisher: Oxford University Press (OUP)
Date: 11-04-1996
Publisher: Oxford University Press (OUP)
Date: 26-08-2015
Publisher: Oxford University Press (OUP)
Date: 05-12-2017
Publisher: EDP Sciences
Date: 29-09-2011
Publisher: Oxford University Press (OUP)
Date: 23-11-2017
Publisher: American Astronomical Society
Date: 15-10-2018
Publisher: American Astronomical Society
Date: 02-05-2016
Publisher: Oxford University Press (OUP)
Date: 21-05-2007
Publisher: American Astronomical Society
Date: 04-1999
DOI: 10.1086/311949
Publisher: American Astronomical Society
Date: 04-2023
Abstract: We present new radial velocity measurements from the Magellan and the Anglo-Australian Telescopes for 175 previously known and 121 newly confirmed globular clusters (GCs) around NGC 5128, the nearest accessible massive early-type galaxy at D = 3.8 Mpc. Remarkably, 28 of these newly confirmed GCs are at projected radii 50 ′ (≳54 kpc), extending to ∼130 kpc, in the outer halo where few GCs had been confirmed in previous work. We identify several subsets of GCs that spatially trace halo substructures that are visible in red giant branch star maps of the galaxy. In some cases, these subsets of GCs are kinematically cold, and may be directly associated with and originate from these specific stellar substructures. From a combined kinematic s le of 645 GCs, we see evidence for coherent rotation at all radii, with a higher rotation litude for the metal-rich GC subpopulation. Using the tracer mass estimator, we measure a total enclosed mass of 2.5 ± 0.3 × 10 12 M ⊙ within ∼120 kpc, an estimate that will be sharpened with forthcoming dynamical modeling. The combined power of stellar mapping and GC kinematics makes NGC 5128 an ongoing keystone for understanding galaxy assembly at mass scales inaccessible in the Local Group.
Publisher: Oxford University Press (OUP)
Date: 17-08-2020
Abstract: Rapidly evolving transients (RETs), also termed fast blue optical transients, are a recently discovered group of astrophysical events that display rapid luminosity evolution. RETs typically rise to peak in less than 10 d and fade within 30, a time-scale unlikely to be compatible with the decay of Nickel-56 that drives conventional supernovae (SNe). Their peak luminosity spans a range of −15 & Mg & −22.5, with some events observed at redshifts greater than 1. Their evolution on fast time-scales has hindered high-quality follow-up observations, and thus their origin and explosion/emission mechanism remains unexplained. In this paper, we present the largest s le of RETs to date, comprising 106 objects discovered by the Dark Energy Survey, and perform the most comprehensive analysis of RET host galaxies. Using deep-stacked photometry and emission lines from OzDES spectroscopy, we derive stellar masses and star formation rates (SFRs) for 49 host galaxies, and metallicities ([O/H]) for 37. We find that RETs explode exclusively in star-forming galaxies and are thus likely associated with massive stars. Comparing RET hosts to s les of host galaxies of other explosive transients as well as field galaxies, we find that RETs prefer galaxies with high specific SFRs (〈log (sSFR)〉 ∼ −9.6), indicating a link to young stellar populations, similar to stripped-envelope SNe. RET hosts appear to show a lack of chemical enrichment, their metallicities akin to long-duration gamma-ray bursts and superluminous SN host galaxies (〈12 + log (O/H)〉 ∼ 9.4). There are no clear relationships between mass or SFR of the host galaxies and the peak magnitudes or decline rates of the transients themselves.
Publisher: Oxford University Press (OUP)
Date: 25-02-2010
DOI: 10.1093/PASJ/62.1.19
Publisher: Elsevier BV
Date: 11-2013
Publisher: American Astronomical Society
Date: 08-08-2011
Publisher: Oxford University Press (OUP)
Date: 13-03-2020
Abstract: We present new Gemini/GMOS optical spectroscopy of 16 extreme variability quasars (EVQs) that dimmed by more than 1.5 mag in the g band between the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey epochs (separated by a few years in the quasar rest frame). These EVQs are selected from quasars in the SDSS Stripe 82 region, covering a redshift range of 0.5 & z & 2.1. Nearly half of these EVQs brightened significantly (by more than 0.5 mag in the g band) in a few years after reaching their previous faintest state, and some EVQs showed rapid (non-blazar) variations of greater than 1–2 mag on time-scales of only months. To increase s le statistics, we use a supplemental s le of 33 EVQs with multi-epoch spectra from SDSS that cover the broad Mg ii λ2798 line. Leveraging on the large dynamic range in continuum variability between the multi-epoch spectra, we explore the associated variations in the broad Mg ii line, whose variability properties have not been well studied before. The broad Mg ii flux varies in the same direction as the continuum flux, albeit with a smaller litude, which indicates at least some portion of Mg ii is reverberating to continuum changes. However, the full width at half-maximum (FWHM) of Mg ii does not vary accordingly as continuum changes for most objects in the s le, in contrast to the case of the broad Balmer lines. Using the width of broad Mg ii to estimate the black hole mass with single epoch spectra therefore introduces a luminosity-dependent bias.
Publisher: Oxford University Press (OUP)
Date: 09-04-2021
Abstract: We present the first Hubble diagram of superluminous supernovae (SLSNe) out to a redshift of two, together with constraints on the matter density, ΩM, and the dark energy equation-of-state parameter, w(≡p/ρ). We build a s le of 20 cosmologically useful SLSNe I based on light curve and spectroscopy quality cuts. We confirm the robustness of the peak–decline SLSN I standardization relation with a larger data set and improved fitting techniques than previous works. We then solve the SLSN model based on the above standardization via minimization of the χ2 computed from a covariance matrix that includes statistical and systematic uncertainties. For a spatially flat Λ cold dark matter (ΛCDM) cosmological model, we find $\\Omega _{\\rm M}=0.38^{+0.24}_{-0.19}$, with an rms of 0.27 mag for the residuals of the distance moduli. For a w0waCDM cosmological model, the addition of SLSNe I to a ‘baseline’ measurement consisting of Planck temperature together with Type Ia supernovae, results in a small improvement in the constraints of w0 and wa of 4 per cent. We present simulations of future surveys with 868 and 492 SLSNe I (depending on the configuration used) and show that such a s le can deliver cosmological constraints in a flat ΛCDM model with the same precision (considering only statistical uncertainties) as current surveys that use Type Ia supernovae, while providing a factor of 2–3 improvement in the precision of the constraints on the time variation of dark energy, w0 and wa. This paper represents the proof of concept for superluminous supernova cosmology, and demonstrates they can provide an independent test of cosmology in the high-redshift (z & 1) universe.
Publisher: Oxford University Press (OUP)
Date: 27-10-2016
Publisher: American Astronomical Society
Date: 31-03-2009
Publisher: IOP Publishing
Date: 2000
Publisher: American Astronomical Society
Date: 16-01-2020
Publisher: Oxford University Press (OUP)
Date: 16-06-2021
Abstract: We present an integral field spectroscopy study of two active galactic nuclei (AGN) in the galaxy cluster RXJ0152–137 at z = 0.84. We have combined integrated and 3D spectra with HST images to perform a complete morpho-kinematical analysis of each galaxy. For G557, we detect narrow and broad H α and [N ii] emission. The broad H α component is redshifted by v ∼ 939 km s−1 concerning the narrow component. The kinematics analysis and VLT/FORS2 data indicate that G557 presents evidence of radial outflows. For G300, it was possible to detect only the broad H α emission. The spectral properties of both galaxies are equivalent to those of local AGN. We also compare the results obtained for each AGN with their location within the cluster. We found a possible connection of the environment with the properties inferred for each of them, and the possible interaction of G557 with an unconfirmed neighboring galaxy, for which a bridge-like structure is observed in the HST images. This work shows evidence of how the same type of AGN can show differences in their spectroscopic properties depending on the region of the cluster in which they develop, which is important to understand how the environment affects AGN and, consequently, the evolution of galaxies.
Publisher: American Astronomical Society
Date: 02-2008
DOI: 10.1086/524881
Publisher: SPIE
Date: 25-10-2004
DOI: 10.1117/12.563009
Publisher: EDP Sciences
Date: 08-2016
Publisher: American Astronomical Society
Date: 14-02-2017
Publisher: European Southern Observatory (ESO)
Date: 2020
Publisher: No publisher found
Date: 2011
Publisher: American Astronomical Society
Date: 05-10-2018
Publisher: Springer Berlin Heidelberg
Date: 2011
Publisher: EDP Sciences
Date: 19-09-2005
Publisher: Springer Science and Business Media LLC
Date: 14-12-2010
DOI: 10.1155/2011/193797
Publisher: American Astronomical Society
Date: 30-07-2018
Publisher: No publisher found
Date: 2008
Publisher: Oxford University Press (OUP)
Date: 17-11-2016
Publisher: No publisher found
Date: 2008
Publisher: Oxford University Press (OUP)
Date: 04-05-2020
Abstract: We use imaging from the first three years of the Dark Energy Survey to characterize the dynamical state of 288 galaxy clusters at 0.1 ≲ z ≲ 0.9 detected in the South Pole Telescope (SPT) Sunyaev–Zeldovich (SZ) effect survey (SPT-SZ). We examine spatial offsets between the position of the brightest cluster galaxy (BCG) and the centre of the gas distribution as traced by the SPT-SZ centroid and by the X-ray centroid eak position from Chandra and XMM data. We show that the radial distribution of offsets provides no evidence that SPT SZ-selected cluster s les include a higher fraction of mergers than X-ray-selected cluster s les. We use the offsets to classify the dynamical state of the clusters, selecting the 43 most disturbed clusters, with half of those at z ≳ 0.5, a region seldom explored previously. We find that Schechter function fits to the galaxy population in disturbed clusters and relaxed clusters differ at z & 0.55 but not at lower redshifts. Disturbed clusters at z & 0.55 have steeper faint-end slopes and brighter characteristic magnitudes. Within the same redshift range, we find that the BCGs in relaxed clusters tend to be brighter than the BCGs in disturbed s les, while in agreement in the lower redshift bin. Possible explanations includes a higher merger rate, and a more efficient dynamical friction at high redshift. The red-sequence population is less affected by the cluster dynamical state than the general galaxy population.
Publisher: Springer Berlin Heidelberg
Date: 26-09-2003
DOI: 10.1007/10854354_50
Publisher: EDP Sciences
Date: 18-07-2005
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We present the first measurements of H i galaxy scaling relations from a blind survey at z 0.15. We perform spectral stacking of 9023 spectra of star-forming galaxies undetected in H i at 0.23 z 0.49, extracted from MIGHTEE-H i Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies in bins of galaxy properties (stellar mass M * , star formation rateSFR, and specific star formation rate sSFR, with sSFR ≡ M * /SFR), obtaining ≳5 σ detections in most cases, the strongest H i -stacking detections to date in this redshift range. With these detections, we are able to measure scaling relations in the probed redshift interval, finding evidence for a moderate evolution from the median redshift of our s le z med ∼ 0.37 to z ∼ 0. In particular, low- M * galaxies ( log 10 ( M * / M ⊙ ) ∼ 9 ) experience a strong H i depletion (∼0.5 dex in log 10 ( M H I / M ⊙ ) ), while massive galaxies ( log 10 ( M * / M ⊙ ) ∼ 11 ) keep their H i mass nearly unchanged. When looking at the star formation activity, highly star-forming galaxies evolve significantly in M H I ( f H I , where f H I ≡ M H I / M * ) at fixed SFR (sSFR), while at the lowest probed SFR (sSFR) the scaling relations show no evolution. These findings suggest a scenario in which low- M * galaxies have experienced a strong H i depletion during the last ∼5 Gyr, while massive galaxies have undergone a significant H i replenishment through some accretion mechanism, possibly minor mergers. Interestingly, our results are in good agreement with the predictions of the simba simulation. We conclude that this work sets novel important observational constraints on galaxy scaling relations.
Publisher: Oxford University Press (OUP)
Date: 25-03-2021
Abstract: We perform a cross validation of the cluster catalogue selected by the red-sequence Matched-filter Probabilistic Percolation algorithm (redMaPPer) in Dark Energy Survey year 1 (DES-Y1) data by matching it with the Sunyaev–Zel’dovich effect (SZE) selected cluster catalogue from the South Pole Telescope SPT-SZ survey. Of the 1005 redMaPPer selected clusters with measured richness $\\hat{\\lambda }\\gt 40$ in the joint footprint, 207 are confirmed by SPT-SZ. Using the mass information from the SZE signal, we calibrate the richness–mass relation using a Bayesian cluster population model. We find a mass trend λ ∝ MB consistent with a linear relation (B ∼ 1), no significant redshift evolution and an intrinsic scatter in richness of σλ = 0.22 ± 0.06. By considering two error models, we explore the impact of projection effects on the richness–mass modelling, confirming that such effects are not detectable at the current level of systematic uncertainties. At low richness SPT-SZ confirms fewer redMaPPer clusters than expected. We interpret this richness dependent deficit in confirmed systems as due to the increased presence at low richness of low-mass objects not correctly accounted for by our richness-mass scatter model, which we call contaminants. At a richness $\\hat{\\lambda }=40$, this population makes up ${\\gt}12{{\\ \\rm per\\ cent}}$ (97.5 percentile) of the total population. Extrapolating this to a measured richness $\\hat{\\lambda }=20$ yields ${\\gt}22{{\\ \\rm per\\ cent}}$ (97.5 percentile). With these contamination fractions, the predicted redMaPPer number counts in different plausible cosmologies are compatible with the measured abundance. The presence of such a population is also a plausible explanation for the different mass trends (B ∼ 0.75) obtained from mass calibration using purely optically selected clusters. The mean mass from stacked weak lensing (WL) measurements suggests that these low-mass contaminants are galaxy groups with masses ∼3–5 × 1013 M⊙ which are beyond the sensitivity of current SZE and X-ray surveys but a natural target for SPT-3G and eROSITA.
Publisher: American Astronomical Society
Date: 27-11-2013
Publisher: American Physical Society (APS)
Date: 21-01-2021
Publisher: Oxford University Press (OUP)
Date: 18-04-2018
DOI: 10.1093/MNRAS/STY957
Publisher: Oxford University Press (OUP)
Date: 15-01-2016
Publisher: Oxford University Press (OUP)
Date: 09-11-2021
Abstract: We present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 & z & 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time.
Publisher: Oxford University Press (OUP)
Date: 06-2007
Publisher: Oxford University Press (OUP)
Date: 23-10-2021
Abstract: We present the statistical methods that have been developed to analyse the OzDES reverberation mapping s le. To perform this statistical analysis we have created a suite of customizable simulations that mimic the characteristics of each source in the OzDES s le. These characteristics include: the variability in the photometric and spectroscopic light curves, the measurement uncertainties, and the observational cadence. By simulating the sources in the OzDES s le that contain the C iv emission line, we developed a set of criteria that rank the reliability of a recovered time-lag depending on the agreement between different recovery methods, the magnitude of the uncertainties, and the rate at which false positives were found in the simulations. These criteria were applied to simulated light curves and these results used to estimate the quality of the resulting Radius–Luminosity relation. We grade the results using three quality levels (gold, silver, and bronze). The input slope of the R–L relation was recovered within 1σ for each of the three quality s les, with the gold standard having the lowest dispersion with a recovered a R–L relation slope of 0.454 ± 0.016 with an input slope of 0.47. Future work will apply these methods to the entire OzDES s le of 771 AGN.
Publisher: American Astronomical Society
Date: 20-11-2015
Publisher: Oxford University Press (OUP)
Date: 26-10-2022
Abstract: Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between colour and luminosity (β) and do not account for varying host-galaxy dust properties. However, from studies of dust in large s les of galaxies, it is known that dust attenuation can vary significantly. Here, we take advantage of state-of-the-art modelling of galaxy properties to characterize dust parameters (dust attenuation AV, and a parameter describing the dust law slope RV) for 1100 Dark Energy Survey (DES) SN host galaxies. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN cosmology: (1) there exists a large range (∼1–6) of host RV (2) high-stellar mass hosts have RV on average ∼0.7 lower than that of low-mass hosts (3) for a subs le of 81 spectroscopically classified SNe there is a significant (& σ) correlation between the Hubble diagram residuals of red SNe Ia and the host RV that when corrected for reduces scatter by $\\sim 13{{\\ \\rm per\\ cent}}$ and the significance of the ‘mass step’ to ∼1σ. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling ‘mass step’ and intrinsic scatter (σint) in SN Ia analyses.
Publisher: Oxford University Press (OUP)
Date: 09-08-2016
Publisher: EDP Sciences
Date: 13-11-2006
Publisher: Walter de Gruyter GmbH
Date: 2008
Abstract: Ionic liquids (ILs) and water are both potentially green solvents that are useful in a variety of extraction processes. This report presents the ternary phase diagrams and tie-line data of trihexyl(tetradecyl)phosphonium dicyanamide [P 6,6,6,14 ][DCA], phosphonium bis(2,4,4-trimethylpentyl)phosphinate [P 6,6,6,14 ][((CH 3 ) 3 C 5 H 8 ) 2 PO 2 ], and 1-ethyl-3-methylimidazolium ethylsulfate [emim][C 2 H 5 SO 4 ] ILs in organic solvents (ethanol, acetonitrile, toluene) and water. [P 6,6,6,14 ][DCA] and [P 6,6,6,14 ][((CH 3 ) 3 C 5 H 8 ) 2 PO 2 ] tended to yield emulsions when combined with water and ethanol, while [emim][C 2 H 5 SO 4 ] combined with toluene and water provided two clear phases of reasonable viscosity. The compositions of the ternary mixtures were determined to obtain the tie-lines. A noticeable difference was observed for the tie-lines of the same IL (e.g., [P 6,6,6,14 ][DCA]) with different organic solvents (ethanol and acetonitrile) and water mixtures. In all cases, the addition of ethanol eventually produced a single phase.
Publisher: Wiley
Date: 10-2005
Abstract: Direct treatment of excess lanthanum, europium or ytterbium metal with 2,6‐dibenzylphenol (HOdbp) at 150 °C afforded [La 2 (Odbp) 6 ], [Eu 2 (Odbp) 4 ] and [Yb(Odbp) 2 ] n , respectively, in high yields. Alternatively, treatment of Yb metal with excess HOdbp gave an ytterbium( III ) species [Yb 2 (Odbp) 6 ], similar to the lanthanum analogue. X‐ray crystal structures were obtained for [La 2 (Odbp) 6 ], [Eu 2 (Odbp) 4 ] and [Yb 2 (Odbp) 6 ]. [La 2 (Odbp) 6 ] and [Yb 2 (Odbp) 6 ] are pseudo‐centrosymmetric dimers with two terminal and four bridging Odbp – ligands and [Eu 2 (Odbp) 4 ] crystallizes as a centrosymmetric dimer with further organization in a polymeric form through supramolecular interactions. All three structurally characterized compounds achieve coordination saturation by Ln–π‐arene interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Publisher: EDP Sciences
Date: 03-09-2009
Publisher: Springer Science and Business Media LLC
Date: 1998
DOI: 10.1038/34124
Publisher: Oxford University Press (OUP)
Date: 16-01-2023
Abstract: Reverberation mapping measurements have been used to constrain the relationship between the size of the broad-line region and luminosity of active galactic nuclei (AGN). This R–L relation is used to estimate single-epoch virial black hole masses, and has been proposed to use to standardize AGN to determine cosmological distances. We present reverberation measurements made with Hβ from the 6-yr Australian Dark Energy Survey (OzDES) Reverberation Mapping Program. We successfully recover reverberation lags for eight AGN at 0.12 & z & 0.71, probing higher redshifts than the bulk of Hβ measurements made to date. Our fit to the R–L relation has a slope of α = 0.41 ± 0.03 and an intrinsic scatter of σ = 0.23 ± 0.02 dex. The results from our multi-object spectroscopic survey are consistent with previous measurements made by dedicated source-by-source c aigns, and with the observed dependence on accretion rate. Future surveys, including LSST, TiDES, and SDSS-V, which will be revisiting some of our observed fields, will be able to build on the results of our first-generation multi-object reverberation mapping survey.
Publisher: No publisher found
Date: 2008
Publisher: Zenodo
Date: 2017
Publisher: American Astronomical Society
Date: 29-04-2019
Publisher: Cambridge University Press (CUP)
Date: 2016
DOI: 10.1017/PASA.2015.52
Abstract: We present a catalogue containing the redshifts of 3 660 X-ray selected targets in the XXL southern field. The redshifts were obtained with the AAOmega spectrograph and 2dF fibre positioner on the Anglo-Australian Telescope. The catalogue contains 1 515 broad line AGN, 528 stars, and redshifts for 41 out of the 49 brightest X-ray selected clusters in the XXL southern field.
Publisher: EDP Sciences
Date: 06-2018
DOI: 10.1051/0004-6361/201731924
Abstract: Aims. We aim to present 70 spectra of 68 new high-redshift type Ia supernovae (SNe Ia) measured at ESO’s VLT during the final two years of operation (2006–2008) of the Supernova Legacy Survey (SNLS). This new s le complements the VLT three year spectral set. Altogether, these two data sets form the five year s le of SNLS SN Ia spectra measured at the VLT on which the final SNLS cosmological analysis will partly be based. In the redshift range considered, this s le is unique in terms of homogeneity and number of spectra. We use it to investigate the possibility of a spectral evolution of SNe Ia populations with redshift as well as SNe Ia spectral properties as a function of lightcurve fit parameters and the mass of the host-galaxy. Methods. Reduction and extraction are based on both IRAF standard tasks and our own reduction pipeline. Redshifts are estimated from host-galaxy lines whenever possible or alternatively from supernova features. We used the spectro-photometric SN Ia model SALT2 combined with a set of galaxy templates that model the host-galaxy contamination to assess the type Ia nature of the candidates. Results. We identify 68 new SNe Ia with redshift ranging from z = 0.207 to z = 0.98 for an average redshift of z = 0.62. Each spectrum is presented in idually along with its best-fit SALT2 model. Adding this new s le to the three year VLT s le of SNLS, the final dataset contains 209 spectra corresponding to 192 SNe Ia identified at the VLT. We also publish the redshifts of other candidates (host galaxies or other transients) whose spectra were obtained at the same time as the spectra of live SNe Ia. This list provides a new redshift catalog useful for upcoming galaxy surveys. Using the full VLT SNe Ia s le, we build composite spectra around maximum light with cuts in color, the lightcurve shape parameter (“stretch”), host-galaxy mass and redshift. We find that high- z SNe Ia are bluer, brighter and have weaker intermediate mass element absorption lines than their low- z counterparts at a level consistent with what is expected from selection effects. We also find a flux excess in the range [3000–3400] Å for SNe Ia in low mass host-galaxies ( M 10 10 M ⊙ ) or with locally blue U – V colors, and suggest that the UV flux (or local color) may be used in future cosmological studies as a third standardization parameter in addition to stretch and color.
Publisher: Springer Science and Business Media LLC
Date: 12-03-2021
DOI: 10.1007/S00109-021-02060-8
Abstract: microRNA are small non-coding RNA molecules which inhibit gene expression by binding mRNA, preventing its translation. As important regulators of gene expression, there is increasing interest in microRNAs as potential diagnostic biomarkers and therapeutic targets. Studies investigating the role of one of the miRNA-miR-652-3p-detail erse roles for this miRNA in normal cell homoeostasis and disease states, including cancers, cardiovascular disease, mental health, and central nervous system diseases. Here, we review recent literature surrounding miR-652-3p, discussing its known target genes and their relevance to disease progression. These studies demonstrate that miR-652-3p targets LLGL1 and ZEB1 to modulate cell polarity mechanisms, with impacts on cancer metastasis and asymmetric cell ision. Inhibition of the NOTCH ligand JAG1 by miR-652-3p can have erse effects on angiogenesis and immune cell regulation. Investigation of miR-652-3p and other dysregulated miRNAs identified a number of pathways potentially regulated by miR-652-3p. This review demonstrates that miR-652-3p has great promise as a diagnostic or therapeutic target due to its activity across multiple cellular systems.
Publisher: EDP Sciences
Date: 08-2013
Publisher: Springer Science and Business Media LLC
Date: 10-1998
DOI: 10.1038/27155
Publisher: American Astronomical Society
Date: 22-03-2013
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201732336
Abstract: We present the 25 square-degree GMRT-XXL-N 610 MHz radio continuum survey, conducted at 50 cm wavelength with the Giant Metrewave Radio Telescope (GMRT) towards the XXL Northern field (XXL-N). We combined previously published observations of the XMM-Large Scale Structure (XMM-LSS) field, located in the central part of XXL-N, with newly conducted observations towards the remaining XXL-N area, and imaged the combined data-set using the Source Peeling and Atmospheric Modeling (SPAM) pipeline. The final mosaic encompasses a total area of 30.4 square degrees, with rms μ Jy beam −1 over 60% of the area. The rms achieved in the inner 9.6 square degree area, enclosing the XMM-LSS field, is about 200 μ Jy beam −1 , while that over the outer 12.66 square degree area (which excludes the noisy edges) is about 45 μ Jy beam −1 . The resolution of the final mosaic is 6.5 arcsec. We present a catalogue of 5434 sources detected at ≥7 ×rms. We verify, and correct the reliability of, the catalog in terms of astrometry, flux, and false detection rate. Making use of the (to date) deepest radio continuum survey over a relatively large (2 square degree) field, complete at the flux levels probed by the GMRT-XXL-N survey, we also assess the survey’s incompleteness as a function of flux density. The radio continuum sensitivity reached over a large field with a wealth of multi-wavelength data available makes the GMRT-XXL-N 610 MHz survey an important asset for studying the physical properties, environments and cosmic evolution of radio sources, in particular radio-selected active galactic nuclei (AGN).
Publisher: EDP Sciences
Date: 26-01-2005
Publisher: WORLD SCIENTIFIC
Date: 03-2001
Publisher: Oxford University Press (OUP)
Date: 27-04-2023
Abstract: The correlation between the broad line region radius and continuum luminosity (R–L relation) of active galactic nuclei (AGNs) is critical for single-epoch mass estimates of supermassive black holes (SMBHs). At z ∼ 1–2, where AGN activity peaks, the R–L relation is constrained by the reverberation mapping (RM) lags of the Mg ii line. We present 25 Mg ii lags from the Australian Dark Energy Survey RM project based on 6 yr of monitoring. We define quantitative criteria to select good lag measurements and verify their reliability with simulations based on both the d ed random walk stochastic model and the rescaled, res led versions of the observed light curves of local, well-measured AGN. Our s le significantly increases the number of Mg ii lags and extends the R–L relation to higher redshifts and luminosities. The relative iron line strength $\\mathcal {R}_{\\rm Fe}$ has little impact on the R–L relation. The best-fitting Mg iiR–L relation has a slope α = 0.39 ± 0.08 with an intrinsic scatter $\\sigma _{\\rm rl} = 0.15^{+0.03}_{-0.02}$ . The slope is consistent with previous measurements and shallower than the H β R–L relation. The intrinsic scatter of the new R–L relation is substantially smaller than previous studies and comparable to the intrinsic scatter of the H β R–L relation. Our new R–L relation will enable more precise single-epoch mass estimates and SMBH demographic studies at cosmic noon.
Publisher: Oxford University Press (OUP)
Date: 20-09-2018
Publisher: EDP Sciences
Date: 24-10-2007
Publisher: Oxford University Press (OUP)
Date: 05-2010
Publisher: American Astronomical Society
Date: 31-10-2011
Publisher: IOP Publishing
Date: 27-11-2018
Publisher: American Astronomical Society
Date: 16-01-2009
Start Date: 2023
End Date: 12-2025
Amount: $758,689.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2015
End Date: 12-2016
Amount: $560,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2016
Amount: $341,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 12-2016
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2011
End Date: 11-2014
Amount: $835,200.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 12-2019
Amount: $360,900.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2010
End Date: 02-2014
Amount: $788,800.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2010
End Date: 11-2013
Amount: $278,400.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2023
Amount: $595,295.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2024
End Date: 03-2031
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded Activity