On Post-Starburst Galaxies Dominating Tidal Disruption Events

TL;DR

This paper proposes that post-starburst galaxies, with their dense central stellar disks, can produce a high rate of tidal disruption events (TDEs) by secondary supermassive black holes, explaining their observed dominance in TDE occurrences.

Contribution

It introduces a model linking post-starburst galaxy features to elevated TDE rates via secondary SMBH interactions with a thin stellar disk, a novel explanation for TDE prevalence.

Findings

Post-starburst galaxies can produce 10^5-10^6 TDEs per galaxy.

Most TDEs occur within 30 million years after the starburst.

The model predicts specific observable signatures of TDEs in PSBs.

Abstract

A starburst induced by a galaxy merger may create a relatively thin central stellar disk at radius $\le 100$pc. We calculate the rate of tidal disruption events (TDEs) by the inspiraling secondary supermassive black (SMBH) through the disk. With a small enough stellar velocity dispersion ($\sigma/v_c \le 0.1$) in the disk, it is shown that $10^5-10^6$ TDEs of solar-type main sequence stars per post-starburst galaxy (PSB) can be produced to explain their dominance in producing observed TDEs. Although the time it takes to bring the secondary SMBH to the disk apparently varies in the range of $\sim 0.1-1$Gyr since the starburst, depending on its landing location and subsequently due to dynamical friction with stars exterior to the central stellar disk in question, the vast majority of TDEs by the secondary SMBH in any individual PSB occurs within a space of time shorter than $\sim 30$Myr. Five unique testable predictions of this model are suggested.