We present new medium resolution , optical long-slit spectra of a sample of 6 UV/optical and 17 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 population , the optical host M _ { BH } distribution has a visible peak near M _ { BH } \sim 10 ^ { 6 } M _ { \odot } , whereas the X-ray host distribution appears flat in M _ { BH } .
We find a subset of X-ray selected candidates that are hosted in galaxies significantly less luminous ( M _ { g } \sim –16 ) and less massive ( stellar mass \sim 10 ^ { 8.5 - 9 } M _ { \odot } ) than those of optical events .
Using statistical tests we find suggestive evidence that , in terms of black hole mass , stellar mass and absolute magnitude , the hard X-ray hosts differ from the UV/optical and soft X-ray samples .
Similar to individual studies , we find that the size of the emission region for the soft X-ray sample is much smaller than the optical emission region , consistent with a compact accretion disk .
We find that the typical Eddington ratio of the soft X-ray emission is \sim 0.01 , as opposed to the optical events which have L _ { BB } \sim L _ { Edd } .
The latter seems artificial if the radiation is produced by self-intersection shocks , and instead suggests a connection to the SMBH .