MUSE IFU observations of galaxies hosting Tidal Disruption Events

TL;DR

This study analyzes TDE host galaxies using MUSE spectroscopy, revealing a strong link between galaxy mergers and TDEs, and providing insights into stellar populations and disrupted star masses near black holes.

Contribution

It presents new observations of EELRs in TDE hosts, especially post-mergers, and constrains the stellar populations and star masses involved in TDEs, highlighting a potential dominance of low-mass stars.

Findings

EELRs detected in 5 out of 20 hosts, mainly in post-merger systems.

Young nuclear populations have ages around 1 Gyr and low stellar masses.

Low-mass stars likely dominate the TDE population, with implications for TDE rates.

Abstract

We present an analysis of twenty tidal disruption event (TDE) host galaxies observed with the MUSE integral-field spectrograph on ESO VLT. We investigate the presence of extended emission line regions (EELRs) and study stellar populations mostly at sub-kpc scale around the host nuclei. EELRs are detected in 5/20 hosts, including two unreported systems. All EELRs are found at z<0.045, suggesting a distance bias and faint EELRs may be missed at higher redshift. EELRs only appear in post-merger systems and all such hosts at z<0.045 show them. Thus, we conclude that TDEs and galaxy mergers have a strong relation, and >45% of post-merger hosts in the sample exhibit EELRs. Furthermore, we constrained the distributions of stellar masses near the central black holes (BHs), using the spectral synthesis code Starlight and BPASS stellar evolution models. The youngest nuclear populations have typical ages of 1 Gyr and stellar masses below 2.5MSun. The populations that can produce observable TDEs around non-rotating BHs are dominated by subsolar-mass stars. 3/4 TDEs requiring larger stellar masses exhibit multi-peaked light curves, possibly implying relation to repeated partial disruptions of high-mass stars. The found distributions are in tension with the masses of the stars derived using light curve models. Mass segregation of the disrupted stars can enhance the rate of TDEs from supersolar-mass stars but our study implies that low-mass TDEs should still be abundant and even dominate the distribution, unless there is a mechanism that prohibits low-mass TDEs or their detection.