Black hole masses of tidal disruption event host galaxies II

Understand

We present new medium resolution, optical long-slit spectra of a sample of 6 UV/optical and 15 X-ray selected tidal disruption event candidate host galaxies.

• We measure emission line ratios from the optical spectra, finding that the large majority of hosts are quiescent galaxies, while those displaying emission lines are generally consistent with star-formation dominated environments; only 3 sources show clear evidence of nuclear activity.
• We measure bulge velocity dispersions using absorption lines and infer host black hole (BH) masses using the M-$\sigma$ relation.
• While the optical and X-ray host BH masses are statistically consistent with coming from the same parent distribution, the optical host distribution has a visible peak near $M_{\rm BH} \sim 10^6 M_\odot$, whereas the X-ray host distribution appears flat in $M_{\rm BH}$.