Gravitational waves from Population III binary black holes are consistent with LIGO/Virgo O3a data for the chirp mass larger than $\sim 20M_{\odot}$

TL;DR

This study shows that Population III binary black hole models with certain initial mass functions can explain the observed distribution of gravitational wave events with larger chirp masses, especially above 20 solar masses.

Contribution

It demonstrates that Population III star models with specific initial mass functions are consistent with LIGO/Virgo O3a data for high-mass black hole mergers.

Findings

Double-peaked distribution in observed data matches Population III models.

Simulation results align with observed mass relations ($M_2 \\approx 0.7 M_1$).

Population III models fit data for chirp masses greater than approximately 20 solar masses.

Abstract

The probability number distribution function of binary black hole mergers observed by LIGO/Virgo O3a has double peaks as a function of chirp mass $M_c$, total mass $M_t$, primary black hole mass $M_1$ and secondary one $M_2$, respectively. The larger chirp mass peak is at $M_c \cong 30 M_{\odot}$. The distribution of $M_2$ vs. $M_1$ follows the relation of $M_2\cong 0.7M_1$. For initial mass functions of Population III stars in the form of $f(M) \propto M^{-\alpha}$, population synthesis numerical simulations with $0\leq \alpha \leq 1.5$ are consistent with O3a data for $M_c \gtrsim 20M_{\odot}$. The distribution of $M_2$ vs. $M_1$ for simulation data also agrees with $M_2\cong 0.7M_1$ relation of O3a data.