Footprints of Population III Stars in the Gravitational-wave Background

Abstract

We investigate detection prospects of the gravitational-wave background (GWB) that originates from the merging of compact objects formed by the collapse of Population III stars. Younger Population I/II stars lead to a GWB in the LIGO/Virgo frequency band at the inspiral phase, while Population III stars would likely show up at the later merger and ringdown phases. We show that, using a network of third-generation detectors, we may be able to separate a Population I/II signal from a Population III one, provided we can subtract individual coalescence events. A detection of a Population III GWB could reveal important information, such as the average redshifted total mass.