Radio emission from simulated tidal disruption events

Abstract

ABSTRACT Several tidal disruption events such as ASASSN-14li and XMMSL1 J0740-85 have recently been observed in the radio. While the radio emission of some tidal disruption events are attributed to a relativistic jet, a few others are associated with a non-relativistic outflow. This outflow can either be due to a spherical wind or unbound tidal debris. We explore this latter hypothesis in this paper. We show that the maximum velocity of the unbound debris is a function of the impact parameter, such that smaller impact parameters (closer approaches) produce larger maximum velocities. We then model this outflow which expands and shocks the local interstellar medium and compute the peak radio flux and frequency as functions of the impact parameter. Moreover, multiple epochs of observations can put additional constraints on the profile of the local interstellar medium. We apply this analysis to four tidal disruption events whose radio emission is attributed to a non-relativistic outflow and show that the velocities of the unbound material are consistent with our simulated events. We also place constraints on the density profile of three of the four tidal disruption events with multiple epochs of observations.