Population of Merging Compact Binaries Inferred Using Gravitational Waves through GWTC-3
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abstract
We report on the population properties of 76 compact binary mergers detected
with gravitational waves below a false alarm rate of 1 per year through GWTC-3.
The catalog contains three classes of binary mergers: BBH, BNS, and NSBH
mergers. We infer the BNS merger rate to be between 10 $\rm{Gpc^{-3} yr^{-1}}$
and 1700 $\rm{Gpc^{-3} yr^{-1}}$ and the NSBH merger rate to be between 7.8
$\rm{Gpc^{-3}\, yr^{-1}}$ and 140 $\rm{Gpc^{-3} yr^{-1}}$ , assuming a constant
rate density versus comoving volume and taking the union of 90% credible
intervals for methods used in this work. Accounting for the BBH merger rate to
evolve with redshift, we find the BBH merger rate to be between 17.9
$\rm{Gpc^{-3}\, yr^{-1}}$ and 44 $\rm{Gpc^{-3}\, yr^{-1}}$ at a fiducial
redshift (z=0.2). We obtain a broad neutron star mass distribution extending
from $1.2^{+0.1}_{-0.2} M_\odot$ to $2.0^{+0.3}_{-0.3} M_\odot$. We can
confidently identify a rapid decrease in merger rate versus component mass
between neutron star-like masses and black-hole-like masses, but there is no
evidence that the merger rate increases again before 10 $M_\odot$. We also find
the BBH mass distribution has localized over- and under-densities relative to a
power law distribution. While we continue to find the mass distribution of a
binary's more massive component strongly decreases as a function of primary
mass, we observe no evidence of a strongly suppressed merger rate above $\sim
60 M_\odot$. The rate of BBH mergers is observed to increase with redshift at a
rate proportional to $(1+z)^{\kappa}$ with $\kappa = 2.9^{+1.7}_{-1.8}$ for
$z\lesssim 1$. Observed black hole spins are small, with half of spin
magnitudes below $\chi_i \simeq 0.25$. We observe evidence of negative aligned
spins in the population, and an increase in spin magnitude for systems with
more unequal mass ratio.
