Examining a Peak-luminosity/Decline-rate Relationship for Tidal Disruption Events

We compare the luminosity, radius, and temperature evolution of the UV/optical blackbodies for 21 well-observed tidal disruption events (TDEs), 8 of which were discovered by the All-Sky Automated Survey for Supernovae. We find that the blackbody radii generally increase prior to peak and slowly decline at late times. The blackbody temperature evolution is generally flat, with a few objects showing small-scale variations. The bolometric UV/optical luminosities generally evolve smoothly and flatten out at late times. Finally, we find an apparent correlation between the peak luminosity and the decline rate of TDEs. This relationship is strongest when comparing the peak luminosity to its decline over 40 days. A linear fit yields ${\mathrm{log}}_{10}({L}_{\mathrm{peak}})$ = $({44.1}_{-0.1}^{+0.1})$ + $({1.6}_{-0.2}^{+0.4})({\rm{\Delta }}{L}_{40}+0.5)$ in cgs, where ${\rm{\Delta }}{L}_{40}={\mathrm{log}}_{10}({L}_{40}/{L}_{\mathrm{peak}})$.