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Abstract

The LIGO, Virgo, and KAGRA (LVK) collaboration has announced 90 coalescing
binary black holes (BBHs) with $p_{\rm astro} > 50\%$ to date, however, the
origin of their formation channels is still an open scientific question. Given
various properties of BBHs (BH component masses and individual spins) inferred
using the default priors by the LVK, independent groups have been trying to
explain the formation of the BBHs with different formation channels. Of all
formation scenarios, the chemically homogeneous evolution (CHE) channel has
stood out with distinguishing features, namely, nearly-equal component masses
and preferentially high individual spins aligned with the orbital angular
momentum. We perform Bayesian inference on the BBH events officially reported
in GWTC-3 with astrophysically-predicted priors representing different
formation channels of the isolated binary evolution (CEE: common-envelope
evolution channel; CHE; SMT: stable mass transfer). Given assumed models, we
report strong evidence for GW190517\_055101 being most likely to have formed
through the CHE channel. Assuming the BBH events in the subsample are all
formed through one of the isolated binary evolution channels, we obtain the
lower limits on the local merger rate density of these channels at $11.45
~\mathrm{Gpc^{-3}~yr^{-1}}$ (CEE), $0.18 ~\mathrm{Gpc^{-3}~yr^{-1}}$ (CHE), and
$0.63 ~\mathrm{Gpc^{-3}~yr^{-1}}$ (SMT) at $90\%$ credible level.