Constraining the origin of stellar binary black hole mergers by detections of their lensed host galaxies and gravitational wave signals

TL;DR

This paper explores how detecting lensed host galaxies of binary black hole mergers with future gravitational wave and galaxy surveys can help determine their origins and formation mechanisms.

Contribution

It introduces a method to use the detection of lensed host galaxies and their spatial distribution to distinguish between different sBBH formation channels.

Findings

Detection fraction varies with survey depth and formation mechanism.

Spatial distribution of lensed sBBHs differs by formation channel.

Future surveys can constrain sBBH origins using lensing signatures.

Abstract

A significant number of stellar binary black hole (sBBH) mergers may be lensed and detected by the third generation gravitational wave (GW) detectors. Their lensed host galaxies may be detectable, which thus helps to accurately localize these sources and provide a new approach to study the origin of sBBHs. In this paper, we investigate the detectability of the lensed host galaxies for the lensed sBBH mergers. We find that the detection fraction of the host galaxies to the lensed GW events can be significantly different for a survey with a given limiting magnitude if sBBHs are produced by different mechanisms, such as the evolution of massive binary stars, the dynamical interactions in dense star clusters, and that assisted by active galactic nuclei or massive black holes. Furthermore, we illustrate that the statistical spatial distribution of those lensed sBBHs in its hosts resulting from different sBBH formation channels can be different from each other. Therefore, with the third generation GW detectors and future large scale galaxy surveys, it is possible to independently constrain the sBBH origin via the detection fraction of those lensed events with identifiable lensing host signatures and/or even constrain the contribution fractions from different sBBH formation mechanisms