Estimating ejecta mass in optical transients

Wild-field optical surveys have detected a lot of transient events in the universe. In particular, novel explosive phenomena have been discovered such as superluminous supernovae, tidal disruption events, and fast blue optical transients, which have unusually large luminosity, short or long duration. While several theoretical models have been proposed, there remain a lot of questions on their origin.

In this talk, I propose a new method to estimate ejected mass in optical transients. Since this method can be applied for the case where optical photons diffuse out of optically thick ejecta, which is true for most optical transients, it can be a strong tool to probe the physical properties of the peculiar optical transients as well as supernovae. After describing the essence of this method, I show the results for supernovae and tidal disruption events. I demonstrate that the estimated ejecta mass constrains some models for optical tidal disruption events. I also plan to talk about the results for superluminous supernovae and other peculiar transients and discuss the implication for the origin of them.