Three-Dimensional Simulations of Tidally Disrupted Solar-Type Stars and the Observational Signatures of Shock Breakout

TL;DR

This paper presents 3D simulations of a solar-type star tidally disrupted by a supermassive black hole, revealing shock-induced surface heating and a distinctive double-peaked X-ray signature as potential observational evidence.

Contribution

The study introduces detailed 3D simulations of stellar tidal disruption, highlighting shock breakout phenomena and their observable X-ray signatures, advancing understanding of star-black hole interactions.

Findings

Strong shocks homogenize stellar temperature profile.

Double-peaked X-ray signature predicted from shock breakout.

Potential detectability of such flares in nearby galaxies.

Abstract

We describe a three-dimensional simulation of a $1 M_{\odot}$ solar-type star approaching a $10^{6} M_{\odot}$ black hole on a parabolic orbit with a pericenter distance well within the tidal radius. While falling towards the black hole, the star is not only stretched along the orbital direction but even more severely compressed at right angles to the orbit. The overbearing degree of compression achieved shortly after pericenter leads to the production of strong shocks which largely homogenize the temperature profile of the star, resulting in surface temperatures comparable to the initial temperature of the star's core. This phenomenon, which precedes the fallback accretion phase, gives rise to a unique double-peaked X-ray signature that, if detected, may be one of the few observable diagnostics of how stars behave under the influence of strong gravitational fields. If $\sim 10^{6} M_{\odot}$ black holes were prevalent in small or even dwarf galaxies, the nearest of such flares may be detectable by EXIST from no further away than the Virgo Cluster.