GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo during the First Half of the Third Observing Run

Abstract

We report on gravitational-wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>15</a:mn><a:mo>∶</a:mo><a:mn>00</a:mn></a:mrow></a:math> UTC and 1 October 2019 <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>15</c:mn><c:mo>∶</c:mo><c:mn>00</c:mn></c:mrow></c:math> UTC. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational-wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near-real time through gamma-ray coordinates network notices and circulars; 13 are reported here for the first time. The catalog contains events whose sources are black hole binary mergers up to a redshift of approximately 0.8, as well as events whose components cannot be unambiguously identified as black holes or neutron stars. For the latter group, we are unable to determine the nature based on estimates of the component masses and spins from gravitational-wave data alone. The range of candidate event masses which are unambiguously identified as binary black holes (both objects <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mo>≥</e:mo><e:mn>3</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:msub><e:mi>M</e:mi><e:mo stretchy="false">⊙</e:mo></e:msub></e:math>) is increased compared to GWTC-1, with total masses from approximately <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mn>14</h:mn><h:mtext> </h:mtext><h:mtext> </h:mtext><h:msub><h:mi>M</h:mi><h:mo stretchy="false">⊙</h:mo></h:msub></h:math> for GW190924_021846 to approximately <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mn>150</k:mn><k:mtext> </k:mtext><k:mtext> </k:mtext><k:msub><k:mi>M</k:mi><k:mo stretchy="false">⊙</k:mo></k:msub></k:math> for GW190521. For the first time, this catalog includes binary systems with significantly asymmetric mass ratios, which had not been observed in data taken before April 2019. We also find that 11 of the 39 events detected since April 2019 have positive effective inspiral spins under our default prior (at 90% credibility), while none exhibit negative effective inspiral spin. Given the increased sensitivity of Advanced LIGO and Advanced Virgo, the detection of 39 candidate events in approximately 26 weeks of data (approximately 1.5 per week) is consistent with GWTC-1. Published by the American Physical Society 2021

Affiliated Institutions

• Gran Sasso Science Institute IT
• National Institute for Space Research BR
• University College Dublin IE
• Université Paris Cité FR
• National Institute for Subatomic Physics NL
• Friedrich Schiller University Jena DE
• California State University System US
• University of Milano-Bicocca IT
• California Institute of Technology US
• Louisiana State University US
• University of Padua IT
• Inter-University Centre for Astronomy and Astrophysics IN
• Monash University AU
• Istituto Nazionale di Fisica Nucleare, Sezione di Torino IT
• Australian National University AU
• Leibniz University Hannover DE
• Korea Institute of Science & Technology Information KR
• University of Minnesota System US
• Université Claude Bernard Lyon 1 FR
• European Gravitational Observatory IT
• University of Illinois Urbana-Champaign US
• Massachusetts Institute of Technology US
• University of Salerno IT
• University of Florida US
• Columbia University US
• Max Planck Institute for Gravitational Physics DE
• University of Pisa IT
• Montclair State University US
• Universitat de Barcelona ES
• Université Paris-Saclay FR
• Syracuse University US
• California State University, Fullerton US
• University of Liège BE
• Christopher Newport University US
• University of Udine IT
• Nicolaus Copernicus Astronomical Center PL
• University of Cambridge GB
• University of Wisconsin–Milwaukee US
• Australian Regenerative Medicine Institute AU
• Montana State University US
• Tata Institute of Fundamental Research IN
• Institute for Plasma Research IN
• Université Grenoble Alpes FR
• University of Glasgow GB
• Bard College US
• Institute for Particle and Nuclear Physics HU
• Stanford University US
• The University of Adelaide AU
• University of Perugia IT
• University of Birmingham GB
• Chennai Mathematical Institute IN
• LIGO Scientific Collaboration US
• University of Strathclyde GB
• National Institute for Astrophysics IT

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