ORCID Profile
0000-0003-4285-6256
Current Organisations
Max-Planck-Institut für Gravitationsphysik
,
University of Wisconsin Milwaukee
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Publisher: American Physical Society (APS)
Date: 06-2004
Publisher: Springer Science and Business Media LLC
Date: 26-04-2018
DOI: 10.1007/S41114-018-0012-9
Abstract: We present possible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron star systems, which are the most promising targets for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and $$90\\%$$ 90 % credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5– $$20~\\mathrm {deg}^2$$ 20 deg 2 requires at least three detectors of sensitivity within a factor of $$\\sim 2$$ ∼ 2 of each other and with a broad frequency bandwidth. When all detectors, including KAGRA and the third LIGO detector in India, reach design sensitivity, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
Publisher: American Physical Society (APS)
Date: 12-05-2005
Publisher: American Physical Society (APS)
Date: 30-04-2004
Publisher: IOP Publishing
Date: 22-01-2008
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-09-2010
Abstract: Einstein@Home, a distributed computing project, discovered a rare, isolated pulsar with a low magnetic field.
Publisher: American Physical Society (APS)
Date: 22-11-2005
Publisher: American Astronomical Society
Date: 18-09-2019
Abstract: The Low-Frequency Array radio telescope discovered the 707 Hz binary millisecond pulsar (MSP) J0952−0607 in a targeted radio pulsation search of an unidentified Fermi gamma-ray source. This source shows a weak energy flux of F γ = 2.6 × 10 −12 erg cm −2 s −1 in the energy range between 100 MeV and 100 GeV. Here we report the detection of pulsed gamma-ray emission from PSR J0952−0607 in a very sensitive gamma-ray pulsation search. The pulsar’s rotational, binary, and astrometric properties are measured over 7 years of Fermi -Large Area Telescope data. For this we take into account the uncertainty on the shape of the gamma-ray pulse profile. We present an updated radio-timing solution now spanning more than 2 years and show results from optical modeling of the black-widow-type companion based on new multiband photometric data taken with HiPERCAM on the Gran Telescopio Canarias on La Palma and ULTRACAM on the New Technology Telescope at ESO La Silla (based on observations collected at the European Southern Observatory, Chile programme 0101.D-0925, PI: Clark, C. J.). PSR J0952−0607 is now the fastest-spinning pulsar for which the intrinsic spin-down rate has been reliably constrained ( ). The inferred surface magnetic field strength of is among the 10 lowest of all known pulsars. This discovery is another ex le of an extremely fast spinning black-widow pulsar hiding within an unidentified Fermi gamma-ray source. In the future such systems might help to pin down the maximum spin frequency and the minimum surface magnetic field strength of MSPs.
Publisher: American Astronomical Society
Date: 18-12-2017
Publisher: Springer Science and Business Media LLC
Date: 11-09-2011
DOI: 10.1038/NPHYS2083
Publisher: American Astronomical Society
Date: 04-08-2015
Publisher: Springer Science and Business Media LLC
Date: 16-10-2017
DOI: 10.1038/NATURE24471
Abstract: On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817-a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first 'multi-messenger' astronomical observation. Such observations enable GW170817 to be used as a 'standard siren' (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic 'distance ladder': the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.
Publisher: IOP Publishing
Date: 12-04-2017
Publisher: American Physical Society (APS)
Date: 12-08-2005
Publisher: American Astronomical Society
Date: 05-07-2013
Publisher: American Physical Society (APS)
Date: 25-10-2005
Publisher: American Physical Society (APS)
Date: 25-10-2005
Publisher: American Astronomical Society
Date: 06-09-2012
Publisher: IOP Publishing
Date: 29-09-2004
Publisher: American Astronomical Society
Date: 16-10-2017
Publisher: IOP Publishing
Date: 21-04-2005
Publisher: American Astronomical Society
Date: 13-05-2014
Publisher: IOP Publishing
Date: 17-11-2008
Publisher: American Astronomical Society
Date: 20-04-2007
DOI: 10.1086/511329
Publisher: American Physical Society (APS)
Date: 02-06-2004
Publisher: American Astronomical Society
Date: 29-07-2013
Publisher: Elsevier BV
Date: 2004
Publisher: IOP Publishing
Date: 09-02-2004
Publisher: American Physical Society (APS)
Date: 27-03-2017
Publisher: American Physical Society (APS)
Date: 28-11-2005
Publisher: American Physical Society (APS)
Date: 08-09-2005
Publisher: American Physical Society (APS)
Date: 07-03-2006
Publisher: IOP Publishing
Date: 29-03-2006
Publisher: American Astronomical Society
Date: 20-12-2011
Publisher: Oxford University Press (OUP)
Date: 27-05-2013
DOI: 10.1093/MNRAS/STT758
Publisher: Wiley
Date: 04-10-2016
Publisher: American Astronomical Society
Date: 26-11-2013
Publisher: IOP Publishing
Date: 24-03-2006
Publisher: Elsevier BV
Date: 05-1983
Publisher: American Astronomical Society
Date: 06-09-2012
Publisher: American Astronomical Society
Date: 10-2020
Abstract: We report the discovery of 1.97 ms period gamma-ray pulsations from the 75 minute orbital-period binary pulsar now named PSR J1653−0158. The associated Fermi Large Area Telescope gamma-ray source 4FGL J1653.6−0158 has long been expected to harbor a binary millisecond pulsar. Despite the pulsar-like gamma-ray spectrum and candidate optical/X-ray associations—whose periodic brightness modulations suggested an orbit—no radio pulsations had been found in many searches. The pulsar was discovered by directly searching the gamma-ray data using the GPU-accelerated Einstein@Home distributed volunteer computing system. The multidimensional parameter space was bounded by positional and orbital constraints obtained from the optical counterpart. More sensitive analyses of archival and new radio data using knowledge of the pulsar timing solution yield very stringent upper limits on radio emission. Any radio emission is thus either exceptionally weak, or eclipsed for a large fraction of the time. The pulsar has one of the three lowest inferred surface magnetic-field strengths of any known pulsar with B surf ≈ 4 × 10 7 G. The resulting mass function, combined with models of the companion star’s optical light curve and spectra, suggests a pulsar mass ≳2 M ⊙ . The companion is lightweight with mass ∼0.01 M ⊙ , and the orbital period is the shortest known for any rotation-powered binary pulsar. This discovery demonstrates the Fermi Large Area Telescope's potential to discover extreme pulsars that would otherwise remain undetected.
Publisher: American Physical Society (APS)
Date: 28-10-2016
Publisher: American Physical Society (APS)
Date: 07-05-2004
Publisher: American Astronomical Society
Date: 07-04-2017
Publisher: American Astronomical Society
Date: 2022
Abstract: We present new discoveries and results from long-term timing of 72 pulsars discovered in the Pulsar Arecibo L -band Feed Array (PALFA) survey, including precise determination of astrometric and spin parameters, and flux density and scatter broadening measurements at 1.4 GHz. Notable discoveries include two young pulsars (characteristic ages ∼30 kyr) with no apparent supernova remnant associations, three mode-changing, 12 nulling and two intermittent pulsars. We detected eight glitches in five pulsars. Among them is PSR J1939+2609, an apparently old pulsar (characteristic age ∼1 Gy), and PSR J1954+2529, which likely belongs to a newly emerging class of binary pulsars. The latter is the only pulsar among the 72 that is clearly not isolated: a nonrecycled neutron star with a 931 ms spin period in an eccentric ( e = 0.114) wide ( P b = 82.7 days) orbit with a companion of undetermined nature having a minimum mass of ∼0.6 M ⊙ . Since operations at Arecibo ceased in 2020 August, we give a final tally of PALFA sky coverage, and compare its 207 pulsar discoveries to the known population. On average, they are 50% more distant than other Galactic plane radio pulsars PALFA millisecond pulsars (MSPs) have twice the dispersion measure per unit spin period than the known population of MSP in the plane. The four intermittent pulsars discovered by PALFA more than double the population of such objects, which should help to improve our understanding of pulsar magnetosphere physics. The statistics for these, rotating radio transients, and nulling pulsars suggest that there are many more of these objects in the Galaxy than was previously thought.
Location: United States of America
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Bruce Allen.