Identifying tidal disruption events among radio transient galaxies

Modern optical-UV time-domain surveys have led to the discovery of two types of variable accretion onto supermassive black holes (SMBHs), both of which can result in the formation of radio jets: the tidal disruption of a passing star by a dormant SMBH leading to transient accretion of stellar debris, and a class of "changing-state" AGNs characterized by spectral state transitions, which can be explained by intrinsic changes in accretion properties. Using modern radio time-domain surveys, such as the ongoing Very Large Array Sky Survey (VLASS), we discovered a group of objects that appeared as new radio sources after two decades of absence. These objects are transient phenomena relative to previous radio surveys and, following a significant increase in radio luminosity, have been classified as radio-loud. We suggest that, for the vast majority of our sources, the radio transient emission event is likely caused by intrinsic changes in accretion properties, similar to what is observed in changing-state AGNs. However, we cannot rule out the possibility that a few of our sources may belong to the rare class of radio-emitting tidal disruption events (TDEs).