Determining the progenitors of merging black-hole binaries

TL;DR

This paper proposes using cross-correlation of gravitational wave events with galaxy catalogs to identify whether black hole mergers originate from stellar evolution or primordial black holes, aiding in understanding their progenitors.

Contribution

It introduces a method to differentiate black hole merger origins by analyzing cross-correlations with galaxy data, forecasting measurement precision for current and future detectors.

Findings

Cross-correlation can distinguish stellar from primordial black hole mergers.

Forecasts show future detectors can identify the origin of high-mass BH mergers.

Method provides a new tool for understanding black hole progenitors.

Abstract

We investigate a possible method for determining the progenitors of black hole (BH) mergers observed via their gravitational wave (GW) signal. We argue that measurements of the cross-correlation of the GW events with overlapping galaxy catalogs may provide an additional tool in determining if BH mergers trace the stellar mass of the Universe, as would be expected from mergers of the endpoints of stellar evolution. If on the other hand the BHs are of primordial origin, as has been recently suggested, their merging would be preferentially hosted by lower biased objects, and thus have a lower cross-correlation with luminous galaxies. Here we forecast the expected precision of the cross-correlation measurement for current and future GW detectors such as LIGO and the Einstein Telescope. We then predict how well these instruments can distinguish the model that identifies high-mass BH-BH mergers as the merger of primordial black holes that constitute the dark matter in the Universe from more traditional astrophysical sources.