# Probing the Black Hole Merger History in Clusters using Stellar Tidal Disruptions

## TL;DR

This paper proposes using electromagnetic signals from stellar tidal disruptions caused by binary black holes in star clusters as a new method to trace their merger history, offering a novel multi-messenger approach.

## Contribution

It introduces a new observable, the variability in tidal disruption events, to distinguish black hole merger pathways in dense star clusters.

## Key findings

- Orbital period distribution peaks on days in globular clusters.
- Tidal disruption variability can map BBH orbital periods.
- Method can differentiate formation scenarios of BBH mergers.

## Abstract

The dynamical assembly of binary black holes (BBHs) in dense star clusters (SCs) is one of the most promising pathways for producing observable gravitational wave (GW) sources, however several other formation scenarios likely operate as well. One of the current outstanding questions is how these different pathways may be distinguished apart. In this paper we suggest a new multi-messenger observable that can be used to constrain the formation of BBH mergers originating from SCs: the electromagnetic signal from tidal disruptions (TDs) of stars by BBHs. Such TDs will show variability in their light curve from the orbital motion of the disruptive BBHs, and can therefore be used to map the BBH orbital period distribution, and thereby also the dynamical mechanisms that eventually drive the BBHs to merger. Using an analytical approach including General Relativistic effects, we find that the orbital period distribution of BBHs within globular clusters peaks on timescales of days, which we argue is unique to this assembly pathway. We propose that the search for variable TDs in current and future EM transient surveys might be used to constrain the merger history of BBHs in SCs.