# Intermediate-Mass Black Holes in Extragalactic Globular Clusters

## TL;DR

This paper discusses the potential of using next-generation radio telescopes to detect intermediate-mass black holes in globular clusters across many galaxies, which could shed light on black hole formation and gravitational wave sources.

## Contribution

It proposes a method to estimate IMBH masses from ngVLA signals and highlights the need for simulations and dynamical models to improve detection and understanding.

## Key findings

- ngVLA can detect IMBHs in GCs up to 25 Mpc away.
- Conversion from radio signals to IMBH mass is based on a semi-empirical model.
- Further simulations and models are needed to refine detection techniques.

## Abstract

Intermediate-mass black holes (IMBHs) have masses of about 100 to 100,000 solar masses. They remain elusive. Observing IMBHs in present-day globular clusters (GCs) would validate a formation channel for seed black holes in the early universe and inform event predictions for gravitational wave facilities. Reaching a large number of GCs per galaxy is key, as models predict that only a few percent will have retained their gravitational-wave fostering IMBHs. Related, many galaxies will need to be examined to establish a robust sample of IMBHs in GCs. These needs can be meet by using a next-generation Very Large Array (ngVLA) to search for IMBHs in the GCs of hundreds of galaxies out to a distance of 25 Mpc. These galaxies hold tens of thousands of GCs in total. We describe how to convert an ngVLA signal from a GC to an IMBH mass according to a semi-empirical accretion model. Simulations of gas flows in GCs would help to improve the robustness of the conversion. Also, self-consistent dynamical models of GCs, with stellar and binary evolution in the presence of IMBHs, would help to improve IMBH retention predictions for present-day GCs.