The observations of gravitational waves (GWs) have revealed the existence of black holes (BHs) above 30M⊙. A variety of scenarios have been proposed as their origin. Among the scenarios, we consider the population III (Pop~III) star scenario. In this scenario, binary black holes (BBHs) containing such massive BHs are naturally produced. We consider Pop~I/II field binaries, Pop~III field binaries and the binaries dynamically formed in globular clusters. We employ a hierarchical Bayesian analysis method and constrain the branching fraction of each formation channel in our universe by using the LIGO-Virgo-KAGRA gravitational wave transient catalog (GWTC-3) events. We find that the Pop~I/II field binary channel dominates the entire merging BBHs. We obtain the branching fraction of the Pop~III BBH channel of 0.11−0.06+0.08, which gives the consistent local merger rate density with the model of Pop~III BBH scenario we adopt. We confirm that BHs arising from the Pop~III channel contribute to massive BBHs in GWTC-3. We also evaluate the branching fraction of each formation channel in the observed BBHs in the GWTC-3 and find the near-equal contributions from the three channels.
@article{arxiv.2312.17491,
title = {Constraint on the progenitor of binary black hole merger using Population III star formation channel},
author = {Masaki Iwaya and Tomoya Kinugawa and Hideyuki Tagoshi},
journal= {arXiv preprint arXiv:2312.17491},
year = {2024}
}