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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog
AU - LIGO Scientific Collaboration and Virgo Collaboration
AU - Pitkin, M
PY - 2021/5/19
Y1 - 2021/5/19
N2 - 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 - + 9.1 20.3 M? or a power law with a Gaussian feature peaking at 33.1 - + 5.6 4.0 M? (90% credible interval). While the primary mass distribution must extend to ~65 M? or beyond, only 2.9 - + 1.7 3.5% 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, c eff. Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing c eff| > 0.01 are dynamically assembled. Third, we estimate merger rates, finding R BBH = 23.9 - + 8.6 14.3 Gpc -3 yr -1 for BBHs and R BNS = 320 - + 240 490 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.
AB - 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 - + 9.1 20.3 M? or a power law with a Gaussian feature peaking at 33.1 - + 5.6 4.0 M? (90% credible interval). While the primary mass distribution must extend to ~65 M? or beyond, only 2.9 - + 1.7 3.5% 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, c eff. Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing c eff| > 0.01 are dynamically assembled. Third, we estimate merger rates, finding R BBH = 23.9 - + 8.6 14.3 Gpc -3 yr -1 for BBHs and R BNS = 320 - + 240 490 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.
KW - Gravitational waves
KW - Astrophysical black holes
KW - Stellar mass black holes
KW - Massive stars
KW - Compact objects
KW - Bayesian statistics
KW - 678
KW - 98
KW - 1611
KW - 732
KW - 288
KW - 1900
U2 - 10.3847/2041-8213/abe949
DO - 10.3847/2041-8213/abe949
M3 - Journal article
VL - 913
SP - L7
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L7
ER -