http://arxiv.org/abs/2201.01905
The coalescing binary black hole (BBH) systems were likely formed in several channels and the identification of them is a challenging task. Previously, people have found out that at the mass of $\sim 34M_\odot$ there is a distinct Gaussian-like peak superposed on the power-law mass function of the primary components. In this work, with the refined \textsc{Power Law + Peak} primary mass distribution models, we identify a population of BBHs with a much stronger preference for equal-mass binaries, which dominates the \textsc{Peak}, for the first time. These BBHs have a pairing function with a $\beta={8.56^{+3.08}{-5.62}}$, or with a $\sigma{\rm m}=3.14^{+4.99}{-1.76}M{\odot}$, where $\sigma_{\rm m}$ represents the width of the distribution of $m_1-m_2$ (i.e., the difference between and the primary and secondly masses). The BBHs in the \textsc{Power Law} have a much flatter pairing function with a $\beta={-0.11^{+2.48}{-1.55}}$. All these parameter ranges are reported for 90\% credibility. Our finding likely points towards the chemically homogeneous evolution channel featured by a high mass ratio for the BBHs with a total mass above $\sim 55 M\odot$. As shown in our simulation, the increase of the GWTC-3 sample by a factor of several would formally establish the presence of the high $q$ population of massive BBHs.
Y. Li, Y. Wang, S. Tang, et. al.
Fri, 7 Jan 22
21/34
Comments: N/A