Title

Population properties of compact objects from the second LIGO-Virgo gravitational-wave transient catalog

Authors

R. Abbott, California Institute of Technology
T. D. Abbott, Louisiana State University
S. Abraham, Inter-University Centre for Astronomy and Astrophysics India
F. Acernese, Università degli Studi di Salerno
K. Ackley, Monash University
A. Adams, Christopher Newport University
C. Adams, LIGO Livingston
R. X. Adhikari, California Institute of Technology
V. B. Adya, The Australian National University
C. Affeldt, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
M. Agathos, University of Cambridge
K. Agatsuma, University of Birmingham
N. Aggarwal, Northwestern University
O. D. Aguiar, Instituto Nacional de Pesquisas Espaciais
L. Aiello, Gran Sasso Science Institute
A. Ain, Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. Ajith, Tata Institute of Fundamental Research, Mumbai
G. Allen, University of Illinois Urbana-Champaign
A. Allocca, Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. A. Altin, The Australian National University
A. Amato, Université Claude Bernard Lyon 1
S. Anand, California Institute of Technology
A. Ananyeva, California Institute of Technology
S. B. Anderson, California Institute of Technology
W. G. Anderson, University of Wisconsin-Milwaukee
S. V. Angelova, University of Strathclyde
S. Ansoldi, Università degli Studi di Udine
J. M. Antelis, Embry-Riddle Aeronautical University, Prescott
S. Antier, Université de Paris
S. Appert, California Institute of Technology
K. Arai, California Institute of Technology
M. C. Araya, California Institute of Technology
J. S. Areeda, California State University, Fullerton

Document Type

Article

Publication Date

5-20-2021

Abstract

We report on the population of 47 compact binary mergers detected with a false-alarm rate of <1 yr-1 in the second LIGO-Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at 39.7-+9.120.3 M? or a power law with a Gaussian feature peaking at 33.1-+5.64.0 M? (90% credible interval). While the primary mass distribution must extend to ~65 M? or beyond, only 2.9-+1.73.5% of systems have primary masses greater than 45 M?. Second, we find that a fraction of BBH systems have component spins misaligned with the orbital angular momentum, giving rise to precession of the orbital plane. Moreover,12%-44% of BBH systems have spins tilted by more than 90°, giving rise to a negative effective inspiral spin parameter, ceff. Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing ceff| > 0.01 are dynamically assembled. Third, we estimate merger rates, finding RBBH = 23.9-+8.614.3 Gpc-3 yr-1 for BBHs and RBNS = 320-+240490 Gpc-3 yr-1 for binary neutron stars. We find that the BBH rate likely increases with redshift (85% credibility) but not faster than the star formation rate (86% credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.

Publication Source (Journal or Book title)

Astrophysical Journal Letters

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