A TIDAL DISRUPTION FLARE IN A1689 FROM AN ARCHIVAL X-RAY SURVEY OF GALAXY CLUSTERS

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 greater than or similar to 30 over at least two years to have maximum L-X(0.3-3.0 keV) greater than or similar to 5 x 10(42) erg s(-1) and to emit as a blackbody with kT similar to 0.12 keV. From the galaxy population as determined by existing studies of the cluster, we estimate a tidal disruption rate of 1.2 x 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-center dot) between 10(6) and 10(8) M-circle dot.