On the structure of tidally-disrupted stellar debris streams

TL;DR

This paper derives a self-similar velocity profile for stellar debris streams from tidal disruption events, providing analytic expressions for their density and stability, with implications for observable signatures.

Contribution

It introduces a simple, self-similar model for debris streams in TDEs, matching numerical results and analyzing their gravitational stability and thermal effects.

Findings

Self-similar velocity profile agrees with numerical simulations.

Derived an approximate radial density profile of debris streams.

Identified a critical adiabatic index for gravitational stability.

Abstract

A tidal disruption event (TDE) -- when a star is destroyed by the immense gravitational field of a supermassive black hole -- transforms a star into a stream of tidally-shredded debris. The properties of this debris ultimately determine the observable signatures of TDEs. Here we derive a simple, self-similar solution for the velocity profile of the debris streams produced from TDEs, and show that this solution agrees extremely well with numerical results. Using this self-similar solution, we calculate an analytic, approximate expression for the radial density profile of the stream. We show that there is a critical adiabatic index that varies as a function of position along the stream above (below) which the stream is unstable (stable) to gravitational fragmentation. We also calculate the impact of heating and cooling on this stability criterion.