Micro Tidal Disruption Events in Active Galactic Nuclei

TL;DR

This paper explores how stars near galactic centers can be tidally disrupted by stellar-mass black holes within AGN disks, proposing micro-TDEs as a new probe of stellar interactions in these environments.

Contribution

It introduces the concept of micro-TDEs in AGNs, estimates their occurrence rate, and discusses their potential as observational probes, including candidate events.

Findings

Micro-TDEs occur at a rate of approximately 170 Gpc$^{-3}$ yr$^{-1}$.

Heavy supermassive black holes can tidally disrupt stars, providing observable signatures.

Two candidate events, ASASSN-15lh and ZTF19aailpwl, are discussed as potential micro-TDEs.

Abstract

Active galactic nuclei (AGNs) can act as black hole assembly lines, funneling some of the stellar-mass black holes from the vicinity of the galactic center into the inner plane of the AGN disk where the black holes can merge through dynamical friction and gravitational wave emission. Here, we show that stars near the galactic center are also brought into the AGN disk, where they can be tidally disrupted by the stellar-mass black holes in the disk. Such micro-tidal disruption events (micro-TDEs) could be useful probe of stellar interaction with the AGN disk. We find that micro-TDEs in AGNs occur at a rate of $\sim170$ Gpc$^{-3}$yr$^{-1}$. Their cleanest observational probe may be the detection of tidal disruption in AGNs by heavy supermassive black holes ($M_{\bullet}\gtrsim10^{8}$ M$_{\odot}$) so that cannot tidally disrupt solar-type stars. We discuss two such TDE candidates observed to date (ASASSN-15lh and ZTF19aailpwl).