Tidal radii of main sequence stars -- II. Simulation methodology and the character of full tidal disruptions

Abstract

This is the second in a series of papers presenting the results of fully general relativistic simulations of stellar tidal disruptions in which the stars' initial states are realistic main-sequence models. We consider eight different stellar masses, from $0.15{\mathrm{M}}_{\odot }$ to $10{\mathrm{M}}_{\odot }$. In the first paper (Ryu et al. 2019a), we gave an overview of this program and discussed the principal observational implications of our work. Here we describe our calculational method and provide details about the outcomes of full disruptions. We find that, relative to the traditional order-of-magnitude estimate $r_{\mathrm{t}}$, the physical tidal radius of low-mass stars is larger by tens of percent, while for high-mass stars ($M_{\star }\gtrsim 1{\mathrm{M}}_{\odot }$) it is smaller by a factor $2-2.5$. The traditional estimate of the range of energies found in the debris is approximately accurate for low-mass stars, but is a factor $\sim 2$ too small for high-mass stars; in addition, the energy distribution for high-mass stars has significant wings. For all stars undergoing tidal encounters, we find that mass-loss continues for a long time because the $instantaneous$ tidal radius, the distance out to which the black hole's tidal gravity competes with the instantaneous stellar gravity at the star's surface, stays comparable to the distance to the black hole until the star has reached $O(10)r_{\mathrm{t}}$. These findings indicate significant failings in the popular "frozen-in" approximation.

arXiv commentWe significantly changed the structure of this paper (with a new title) as a response to the referee's report. We emphasize that our results have not been changed, but added more explanations for our numerical methods. We submitted the new version with the new title (arXiv:2001.03502)

References in corpus (5)

• LSST Science Book, Version 2.0
• eROSITA Science Book: Mapping the Structure of the Energetic Universe
• Thawing the frozen-in approximation: implications for self-gravity in deeply plunging tidal disruption events
• Hydrodynamical moving-mesh simulations of the tidal disruption of stars by supermassive black holes
• Tidal radii of main sequence stars -- I. Physical tidal radius, semi-analytic model and their implications

Cited by in corpus (3)

• Tidal disruptions of main sequence stars -- III. Stellar mass dependence of the character of partial disruptions
• Measuring black hole masses from tidal disruption events and testing the $M_{\mathrm{BH}}-{\sigma }_{\ast }$ relation
• Tidal radii of main sequence stars -- III. Partial disruptions