Deep spectroscopy of the MV ∼ −14.8 host galaxy of a tidal disruption flare in A1795★.

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 × 108 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 ≳104. 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. [ABSTRACT FROM PUBLISHER]