Changing-Look AGN Behaviour Induced by Disk-Captured Tidal Disruption Events

TL;DR

This paper proposes that the interaction between accretion disks and retrograde stars in galactic nuclei can significantly increase tidal disruption event rates, explaining the frequent changing-look phenomena in active galactic nuclei.

Contribution

It introduces a novel disk capture mechanism that enhances TDE rates, providing a new explanation for the variability in changing-look AGNs compared to traditional models.

Findings

Disk capture process can boost TDE rates by several orders of magnitude.

Enhanced TDE rates align with observed high-energy variability in changing-look AGNs.

The model explains the rapid and frequent transitions in AGN activity.

Abstract

Recent observations of changing-look active galactic nuclei (AGN) hint at a frequency of accretion activity not fully explained by tidal disruption events (TDEs) stemming from relaxation processes in nucleus star clusters (NSCs), traditionally estimated to occur at rates of $10^{-4}$ to $10^{-5}$ yr$^{-1}$ per galaxy. In this letter, we propose an enhanced TDE rate through the AGN disk capture process, presenting a viable explanation for the frequent transitions observed in changing-look AGN. Specifically, we investigate the interaction between the accretion disk and retrograde stars within NSCs, resulting in the rapid occurrence of TDEs within a condensed time frame. Through detailed calculations, we derive the time-dependent TDE rates for both relaxation-induced TDE and disk-captured TDE. Our analysis reveals that TDEs triggered by the disk capture process can notably amplify the TDE rate by several orders of magnitude during the AGN phase. This mechanism offers a potential explanation for the enhanced high-energy variability characteristic of changing-look AGNs.