Disk Wind-Driven Expanding Radio-emitting Shell in Tidal Disruption Events

We study the evolution of a nonrelativistically expanding thin shell in radio-emitting tidal disruption events (TDEs) based on a one-dimensional spherically symmetric model considering the effect of both a time-dependent mass-loss rate of the disk wind and the ambient mass distribution. The analytical solutions are derived in two extreme limits; one is the approximate solution near the origin in the form of the Taylor series, and the other is the asymptotic solution in which the ambient matter is dominant far away from the origin. Our numerical solutions are confirmed to agree with the respective analytical solutions. We find that no simple power law of the time solution exists in early to middle times because the mass-loss rate varies over time, affecting the shell dynamics. We also discuss the application of our model to the observed radio-emitting TDE, AT 2019dsg.