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\nhole at the center of a galaxy can under most circumstances be expected to emit\na giant flare of radiation as it is disrupted and a portion of the resulting\nstream of shock-heated stellar debris falls back onto the black hole itself. We\nexamine the first results of an ongoing archival survey of galaxy clusters\nusing Chandra and XMM-selected data, and report a likely tidal disruption flare\nfrom SDSS J131122.15-012345.6 in Abell 1689. The flare is observed to vary by a\nfactor of >30 over at least 2 years, to have maximum L_X(0.3-3.0 keV)> 5 x\n10^{42} erg s^{-1} and to emit as a blackbody with kT~0.12 keV. From the galaxy\npopulation as determined by existing studies of the cluster, we estimate a\ntidal disruption rate of 1.2 x 10^{-4} galaxy^{-1} year^{-1} if we assume a\ncontribution to the observable rate from galaxies whose range of luminosities\ncorresponds to a central black hole mass (M_bh) between 10^6 and 10^8 M_sun.\n