Radiative diffusion in a time-dependent outflow: a model for fast blue optical transients

Understand

Fast Blue Optical Transients (FBOTs) are luminous transients with fast evolving (typically $t_{\rm rise}<12\ \rm days$) light curve and blue color (usually $\rm {-0.2\ >\ g-r\ >\ -0.3}$) that cannot be explained by a supernova-like explosion.

• We propose a radiative diffusion in a time-dependent outflow model to interpret such special transients.
• In this model, we assume a central engine ejects continuous outflow during a few days.
• We consider the ejection of the outflow to be time-dependent.