Variability as a new discovery channel for Intermediate-Mass Black Holes in the Time Domain Era

TL;DR

This paper proposes that variability studies in the time domain, especially with upcoming observatories like Rubin, can uncover intermediate-mass black holes, filling a key gap in understanding black hole evolution.

Contribution

It introduces variability as a novel detection channel for IMBHs, emphasizing the potential of time-domain surveys to identify these elusive objects.

Findings

Time-domain variability is a promising method to detect IMBHs.

Upcoming observatories like Rubin will enhance IMBH detection capabilities.

Detecting IMBHs will fill critical gaps in black hole formation theories.

Abstract

Between the groundbreaking detections of stellar-mass black holes by LIGO/Virgo/KAGRA and JWST's revelation of a surprisingly abundant population of supermassive black holes, one crucial missing link remains: the elusive intermediate-mass black holes (IMBHs). IMBHs represent a key phase in the hierarchical growth of black holes, yet they have persistently evaded detection. Traditional methods, effective for both actively accreting and quiescent black holes, have largely failed to uncover this hidden population. Here, we argue that novel observational strategies--particularly time-domain variability studies of active galactic nuclei (AGN) and tidal disruption events--provide a promising path forward. Finding IMBHs will resolve critical gaps in our understanding of black hole formation and the various mechanisms driving their subsequent growth. The upcoming Vera C. Rubin Observatory, with its unprecedented capacity to monitor the dynamic sky, stands to revolutionize our ability to detect these long-sought IMBHs, shedding new light on the assembly history of black holes across cosmic time.