A Tidal Disruption Event in a nearby Galaxy Hosting an Intermediate Mass Black Hole
Troja, E.; Butler, N. R.; Cenko, S. B.; Covino, S.; Kutyrev, A.; Campana, S.; Fugazza, D.; Fox, O.; Cheung, C. C.; Pursimo, T.; Donato, D.; Landt, H.
United States, Italy, Spain, United Kingdom
Abstract
We report the serendipitous discovery of a bright point source flare in the Abell cluster A1795 with archival EUVE and Chandra observations. Assuming the EUVE emission is associated with the Chandra source, the X-ray 0.5-7 keV flux declined by a factor of ~2300 over a time span of 6 yr, following a power-law decay with index ~2.44 ± 0.40. The Chandra data alone vary by a factor of ~20. The spectrum is well fit by a blackbody with a constant temperature of kT ~ 0.09 keV (~106 K). The flare is spatially coincident with the nuclear region of a faint, inactive galaxy with a photometric redshift consistent at the 1σ level with the cluster (z = 0.062476). We argue that these properties are indicative of a tidal disruption of a star by a black hole (BH) with log (M BH/M ⊙) ~ 5.5 ± 0.5. If so, such a discovery indicates that tidal disruption flares may be used to probe BHs in the intermediate mass range, which are very difficult to study by other means.