Tidal disruption event Calorimetry: Observational constraints on the physics of TDE optical flares

Tidal disruption events are routinely discovered as bright optical/UV flares, the properties of which are now well categorized on the population level. The underlying physical processes that produce the evolution of their X-ray emission and their long-lasting UV/optical plateau are well understood; however, the origin of their early-time optical/UV emission remains the subject of much debate and uncertainty. In this paper we propose and perform ``Calorimetric'' tests of published theories of these optical flares, contrasting theoretical predictions for the scaling of the radiated energy and peak luminosity of these flares with black hole mass (something which is predicted by each theory), with the observed (positive) black hole mass scaling. No one theory provides a satisfactory description of observations at all black hole mass scales. Theories relating to the reprocessing of an Eddington-limited compact accretion disk, or emission (energy) released in the formation of a Keplerian disk near the circularisation radius, perform best, but require extending. Models whereby the optical/UV flare are directly produced by shocks between debris streams (e.g., TDEmass), or the efficient reprocessing of the fallback rate (e.g., MOSFIT, or any other model in which $L \propto \dot{M}_{\mathrm{fb}}$), are ruled out at high $(>5σ)$ significance by the data.