The bulge masses of TDE host galaxies and their scaling with black hole mass

Tidal disruption events (TDEs) provide a means to probe the low end of the supermassive black hole (SMBH) mass distribution, as they are only observable below the Hills mass (less than or similar to 10(8) M-circle dot). Here, we attempt to calibrate the scaling of SMBH mass with host galaxy bulge mass, enabling SMBH masses to be estimated for large TDE samples without the need for follow-up observations or extrapolations of relations based on high-mass samples. We derive host galaxy masses using prospector fits to the UV-MIR spectral energy distributions for the hosts of 29 well-observed TDEs with BH mass estimates from mosfit. We then conduct detailed bulge/disc decomposition using SDSS and PanSTARRS imaging, and provide a catalogue of bulge masses. We measure a positive correlation between SMBH and bulge mass for the TDE sample, with a power-law slope of 0.28 and significance p = 0.06 (Spearmans) and p = 0.05 (Pearsons), and an intrinsic scatter of 0.2 dex. Applying MC resampling and bootstrapping, we find a more conservative estimate of the slope is 0.18 +/- 0.11, dominated by the systematic errors from prospector and mosfit. This is shallower than the slope at high SMBH mass, which may be due to a bias in the TDE sample towards lower mass BHs that can more easily disrupt low-mass stars outside of the event horizon. When combining the TDE sample with that of the high-mass regime, we find that TDEs are successful in extending the SMBH - stellar mass relationship further down the mass spectrum and provide a relationship across the full range of SMBH masses.

Automated summary

This study investigates the relationship between supermassive black hole (SMBH) mass and host galaxy bulge mass using tidal disruption events (TDEs). The results show a positive correlation between SMBH and bulge mass, providing a way to estimate SMBH masses for large TDE samples without the need for follow-up observations or extrapolations.