Publication Date:
2014-08-25
Description:
A likely tidal disruption of a star by the intermediate-mass black hole (IMBH) of a dwarf galaxy was recently identified in association with Abell 1795. Without deep spectroscopy for this very faint object, however, the possibility of a more massive background galaxy or even a disc-instability flare from a weak active galactic nucleus (AGN) could not be dismissed. We have now obtained 8 h of Gemini spectroscopy which unambiguously demonstrates that the host galaxy is indeed an extremely low mass ( M * ~ 3 10 8 M ) galaxy in Abell 1795, comparable to the least massive galaxies determined to host IMBHs via other studies. We find that the spectrum is consistent with the X-ray flare being due to a tidal disruption event rather than an AGN flare. We also set improved limits on the black hole mass (log[ M • /M ] ~ 5.3–5.7) and infer a 15 yr X-ray variability of a factor of 10 4 . The confirmation of this galaxy–black hole system provides a glimpse into a population of galaxies that is otherwise difficult to study, due to the galaxies’ low masses and intrinsic faintness, but which may be important contributors to the tidal disruption rate.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
