A simple and accurate prescription for the tidal disruption radius of a star and the peak accretion rate in tidal disruption events

Eric R. Coughlin, C. J. Nixon

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

A star destroyed by a supermassive black hole (SMBH) in a tidal disruption event (TDE) enables the study of SMBHs. We propose that the distance within which a star is completely destroyed by an SMBH, defined rt,c, is accurately estimated by equating the SMBH tidal field (including numerical factors) to the maximum gravitational field in the star. We demonstrate that this definition accurately reproduces the critical βc = rt/rt,c, where rt = R∗(M•/M∗)1/3 is the standard tidal radius with R∗ and M∗ the stellar radius and mass, and M• the SMBH mass, for multiple stellar progenitors at various ages, and can be reasonably approximated by βc ≲ [ρc/(4ρ∗)]1/3, where ρc (ρ∗) is the central (average) stellar density. We also calculate the peak fallback rate and time at which the fallback rate peaks, finding excellent agreement with hydrodynamical simulations, and also suggest that the partial disruption radius - the distance at which any mass is successfully liberated from the star - is βpartial ≲ 4-1/3 ≲ 0.6. For given stellar and SMBH populations, this model yields, e.g. the fraction of partial TDEs, the peak luminosity distribution of TDEs, and the number of directly captured stars.

Original languageEnglish (US)
Pages (from-to)L26-L30
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume517
Issue number1
DOIs
StatePublished - Nov 1 2022

Keywords

  • black hole physics
  • methods: analytical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'A simple and accurate prescription for the tidal disruption radius of a star and the peak accretion rate in tidal disruption events'. Together they form a unique fingerprint.

Cite this