A Tidal Disruption Flare in A1689 from an Archival X-ray Survey of Galaxy Clusters

Abstract

Theory suggests that a star making a close passage by a supermassive black hole at the center of a galaxy can under most circumstances be expected to emit a giant flare of radiation as it is disrupted and a portion of the resulting stream of shock-heated stellar debris falls back onto the black hole itself. We examine the first results of an ongoing archival survey of galaxy clusters using Chandra and XMM-Newton-selected data and report a likely tidal disruption flare from SDSS J131122.15-012345.6 in A1689. The flare is observed to vary by a factor of gsim30 over at least two years to have maximum L_X (0.3-3.0 keV) >~ 5 × 10⁴² erg s^-1 and to emit as a blackbody with kT ~ 0.12 keV. From the galaxy population as determined by existing studies of the cluster, we estimate a tidal disruption rate of 1.2 × 10^-4 galaxy^-1 yr^-1 if we assume a contribution to the observable rate from galaxies whose range of luminosities corresponds to a central black hole mass (M _•) between 10⁶ and 10⁸ M _sun.