Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA’s Binary Black Holes Form Dynamically

Isobel Romero-Shaw; Paul D. Lasky; Eric Thrane

doi:10.3847/1538-4357/ac9798

Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA’s Binary Black Holes Form Dynamically

Isobel Romero-Shaw, Paul D. Lasky, Eric Thrane

School of Physics and Astronomy

Research output: Contribution to journal › Article › Research › peer-review

83 Citations (Scopus)

Abstract

The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the LIGO-Virgo-KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find that at least four of these events show significant support for eccentricity e ₁₀ ≥ 0.1 at a gravitational-wave frequency of 10 Hz (>60% credibility, under a log-uniform eccentricity prior that spans the range 10⁻⁴ < e ₁₀ < 0.2). Two of these events are new additions to the population: GW191109 and GW200208_22. If the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100% of the observed mergers. However, it remains likely that other formation environments with higher yields of eccentric mergers—for example, active galactic nuclei—also contribute. We estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e ₁₀ ≥ 0.05 at LIGO-Virgo sensitivity, with only ∼5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors.

Original language	English
Article number	171
Number of pages	18
Journal	The Astrophysical Journal
Volume	940
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/ac9798
Publication status	Published - 1 Dec 2022

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10.3847/1538-4357/ac9798Licence: CC BY

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@article{948a4f184f484fc8805011e4d4837003,

title = "Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA{\textquoteright}s Binary Black Holes Form Dynamically",

abstract = "The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the LIGO-Virgo-KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find that at least four of these events show significant support for eccentricity e 10 ≥ 0.1 at a gravitational-wave frequency of 10 Hz (>60\% credibility, under a log-uniform eccentricity prior that spans the range 10−4 < e 10 < 0.2). Two of these events are new additions to the population: GW191109 and GW200208\_22. If the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100\% of the observed mergers. However, it remains likely that other formation environments with higher yields of eccentric mergers—for example, active galactic nuclei—also contribute. We estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e 10 ≥ 0.05 at LIGO-Virgo sensitivity, with only ∼5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors.",

author = "Isobel Romero-Shaw and Lasky, \{Paul D.\} and Eric Thrane",

note = "Funding Information: We thank Vijay Varma, Katerina Chatziioannou, Alan Knee, Teagan Clarke, Makai Baker, and attendees of the Niels Bohr Institute{\textquoteright}s Workshop on Black Hole Dynamics for enlightening suggestions, observations, and discussions. We also thank Mike Zevin for his insights on our work and comments on our manuscript. We are grateful to our anonymous reviewer, whose advice on our manuscript improved its contents. This work is supported by the Australian Research Council Centre of Excellence CE170100004, and the Discovery Project DP220101610. I.R.-S. acknowledges support received from the Herchel Smith Postdoctoral Fellowship Fund. The authors are grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation (NSF) Grants PHY-0757058 and PHY-0823459. This research has made use of data or software obtained from the Gravitational Wave Open Science Center (gw-openscience.org), a service of LIGO Laboratory, the LIGO Scientific Collaboration, the Virgo Collaboration, and KAGRA. LIGO Laboratory and Advanced LIGO are funded by the United States NSF as well as by the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society, and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and the construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory, by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN), and the Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan, Monaco, Poland, Portugal, and Spain. The construction and operation of KAGRA are funded by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) and the Japan Society for the Promotion of Science (JSPS), the National Research Foundation and the Ministry of Science and ICT (MSIT) in Korea, and Academia Sinica (AS) and the Ministry of Science and Technology (MoST) in Taiwan. Publisher Copyright: {\textcopyright} 2022. The Author(s). Published by the American Astronomical Society.",

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doi = "10.3847/1538-4357/ac9798",

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T1 - Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA’s Binary Black Holes Form Dynamically

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AU - Lasky, Paul D.

AU - Thrane, Eric

N1 - Funding Information: We thank Vijay Varma, Katerina Chatziioannou, Alan Knee, Teagan Clarke, Makai Baker, and attendees of the Niels Bohr Institute’s Workshop on Black Hole Dynamics for enlightening suggestions, observations, and discussions. We also thank Mike Zevin for his insights on our work and comments on our manuscript. We are grateful to our anonymous reviewer, whose advice on our manuscript improved its contents. This work is supported by the Australian Research Council Centre of Excellence CE170100004, and the Discovery Project DP220101610. I.R.-S. acknowledges support received from the Herchel Smith Postdoctoral Fellowship Fund. The authors are grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation (NSF) Grants PHY-0757058 and PHY-0823459. This research has made use of data or software obtained from the Gravitational Wave Open Science Center (gw-openscience.org), a service of LIGO Laboratory, the LIGO Scientific Collaboration, the Virgo Collaboration, and KAGRA. LIGO Laboratory and Advanced LIGO are funded by the United States NSF as well as by the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society, and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and the construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory, by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN), and the Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan, Monaco, Poland, Portugal, and Spain. The construction and operation of KAGRA are funded by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) and the Japan Society for the Promotion of Science (JSPS), the National Research Foundation and the Ministry of Science and ICT (MSIT) in Korea, and Academia Sinica (AS) and the Ministry of Science and Technology (MoST) in Taiwan. Publisher Copyright: © 2022. The Author(s). Published by the American Astronomical Society.

PY - 2022/12/1

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N2 - The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the LIGO-Virgo-KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find that at least four of these events show significant support for eccentricity e 10 ≥ 0.1 at a gravitational-wave frequency of 10 Hz (>60% credibility, under a log-uniform eccentricity prior that spans the range 10−4 < e 10 < 0.2). Two of these events are new additions to the population: GW191109 and GW200208_22. If the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100% of the observed mergers. However, it remains likely that other formation environments with higher yields of eccentric mergers—for example, active galactic nuclei—also contribute. We estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e 10 ≥ 0.05 at LIGO-Virgo sensitivity, with only ∼5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors.

AB - The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the LIGO-Virgo-KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find that at least four of these events show significant support for eccentricity e 10 ≥ 0.1 at a gravitational-wave frequency of 10 Hz (>60% credibility, under a log-uniform eccentricity prior that spans the range 10−4 < e 10 < 0.2). Two of these events are new additions to the population: GW191109 and GW200208_22. If the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100% of the observed mergers. However, it remains likely that other formation environments with higher yields of eccentric mergers—for example, active galactic nuclei—also contribute. We estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e 10 ≥ 0.05 at LIGO-Virgo sensitivity, with only ∼5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors.

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JO - The Astrophysical Journal

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ER -

Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA’s Binary Black Holes Form Dynamically

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Precision cosmic expansion in the era of gravitational-wave astronomy

ARC Centre of Excellence for Gravitational Wave Discovery

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Four Eccentric Mergers Increase the Evidence that LIGO-Virgo-KAGRA’s Binary Black Holes Form Dynamically

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Precision cosmic expansion in the era of gravitational-wave astronomy

ARC Centre of Excellence for Gravitational Wave Discovery

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