How to confirm the existence of population III stars by observations of gravitational waves

TL;DR

This paper proposes a method to confirm the existence of Population III stars through gravitational wave observations by analyzing black hole merger events and distinguishing models with and without Pop III stars.

Contribution

It introduces a statistical approach using likelihood ratios to identify Pop III stars from GW data, demonstrating its effectiveness with simulated detections.

Findings

Can distinguish Pop I/II from Pop I/II/III models with 90% probability using 22 GW signals

Method effectively evaluates the likelihood of Pop III star existence from GW observations

Simulation results support the feasibility of confirming Pop III stars via gravitational waves

Abstract

We propose a method for confirmation of the existence of Population III (Pop III) stars with massive black hole binaries as GW150914 in gravitational wave (GW) observation. When we get enough number of events, we want to determine which model is closer to reality, with and without Pop III stars. We need to prepare various "Pop I/II models" and various "Pop I/II/III models" and investigate which model is consistent with the events. To demonstrate our analysis, we simulate detections of GW events for some examples of population synthesis models with and without Pop III stars. We calculate the likelihood ratio with the realistic number of events and evaluate the probability of identifying the existence of Pop III stars. In typical cases, our analysis can distinguish between Pop I/II model and Pop I/II/III model with 90% probability by 22 GW signals from black hole-black hole binary mergers.