Tidal disruption flares from stars on eccentric orbits

TL;DR

This study uses 3D simulations to analyze how stars on eccentric orbits around supermassive black holes are tidally disrupted, revealing that eccentricity significantly affects debris fallback and accretion rates.

Contribution

It introduces a detailed simulation-based analysis of tidal disruption for stars on eccentric orbits, highlighting a critical eccentricity threshold affecting debris fallback.

Findings

Mass fallback rate follows -5/3 decay for parabolic orbits.

Eccentric orbits below a critical eccentricity result in all debris being bound.

Fallback rates can exceed Eddington accretion and differ from standard models.

Abstract

We study tidal disruption and subsequent mass fallback for stars approaching supermassive black holes on bound orbits, by performing three dimensional Smoothed Particle Hydrodynamics simulations with a pseudo-Newtonian potential. We find that the mass fallback rate decays with the expected -5/3 power of time for parabolic orbits, albeit with a slight deviation due to the self-gravity of the stellar debris. For eccentric orbits, however, there is a critical value of the orbital eccentricity, significantly below which all of the stellar debris is bound to the supermassive black hole. All the mass therefore falls back to the supermassive black hole in a much shorter time than in the standard, parabolic case. The resultant mass fallback rate considerably exceeds the Eddington accretion rate and substantially differs from the -5/3 power of time.