Stellar tidal disruption events in general relativity

Nicholas C. Stone, Michael Kesden, Roseanne M. Cheng, Sjoert van Velzen

Research output: Contribution to journalReview articlepeer-review

Abstract

A tidal disruption event (TDE) ensues when a star passes too close to a supermassive black hole (SMBH) in a galactic center, and is ripped apart by its tidal field. The gaseous debris produced in a TDE can power a bright electromagnetic flare as it is accreted by the SMBH; so far, several dozen TDE candidates have been observed. For SMBHs with masses above ∼ 10 7 M , the tidal disruption of solar-type stars occurs within ten gravitational radii of the SMBH, implying that general relativity (GR) is needed to describe gravity. Three promising signatures of GR in TDEs are: (1) a super-exponential cutoff in the volumetric TDE rate for SMBH masses above ∼ 10 8 M due to direct capture of tidal debris by the event horizon, (2) delays in accretion disk formation (and a consequent alteration of the early-time light curve) caused by the effects of relativistic nodal precession on stream circularization, and (3) quasi-periodic modulation of X-ray emission due to global precession of misaligned accretion disks and the jets they launch. We review theoretical models and simulations of TDEs in Newtonian gravity, then describe how relativistic modifications give rise to these proposed observational signatures, as well as more speculative effects of GR. We conclude with a brief summary of TDE observations and the extent to which they show indications of these predicted relativistic signatures.

Original languageAmerican English
Article number30
JournalGeneral Relativity and Gravitation
Volume51
Issue number2
DOIs
StatePublished - 1 Feb 2019
Externally publishedYes

Keywords

  • Black hole spin
  • General relativity
  • Relativistic astrophysics
  • Testing Kerr spacetime
  • Tidal disruption event

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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