Investigating the Circumnuclear Medium of Tidal Disruption Events with Radio Observations

TL;DR

This study uses radio observations of 53 TDEs to analyze the circumnuclear medium density profile by applying the closure relation, providing insights into SMBH environments and accretion history.

Contribution

It introduces a method to constrain the CNM density profile in TDEs using the closure relation applied to a large radio TDE sample, enhancing understanding of SMBH environments.

Findings

CNM density profiles are consistent with equipartition estimates.

Closure relation analysis effectively probes the CNM environment.

Results support the use of CR in studying quiescent SMBH surroundings.

Abstract

Tidal disruption events (TDEs) are unique tools for investigating quiescent supermassive black hole (SMBH), accretion physics, and circumnuclear medium (CNM) environments. The CNM density profile is of great astrophysical significance, since it provides key diagnostics for the accretion history of dormant SMBH. TDEs can launch outflows that produce radio emission when propagating into the CNM. The closure relation (CR), i.e., the relation between the temporal indices and the spectral indices, are therefore monitoring the CNM density profile. In this work, we first collect 53 TDEs with radio observations to date. We then obtain the predicted CR for arbitrary CNM and different dynamical phases of the outflow, and apply to the radio TDE sample. We constrain the CNM density profile for 26 radio TDEs with good data quality. The results are generally consistent with those estimated with equipatition method, suggesting that CR analysis is efficient in the study of CNM profile for a quiescent SMBH.