Moving-mesh radiation-hydrodynamic simulations of wind-reprocessed
  transients
  Motivated by recent theoretical work on tidal disruption events and other
peculiar transients, we present moving-mesh radiation-hydrodynamic simulations
of radiative luminosity emitted by a central source being reprocessed by a
wind-like outflow. We couple the moving-mesh hydrodynamic code JET with our
newly-developed radiation module based on mixed-frame grey flux-limited
diffusion with implicit timestep update. This allows us to study the
self-consistent multi-dimensional radiation-hydrodynamic evolution over more
than ten orders of magnitude in both space and time in a single run. We
simulate an optically-thick spherical wind with constant or evolving mass-loss
rate, which is irradiated by a central isotropic or angularly-dependent
radiation source. Our spherically-symmetric simulations confirm previous
analytic results by identifying different stages of radiation reprocessing:
radiation trapped in the wind, diffusing out through the wind, and reaching
constant maximum attenuation. We find that confining the central radiation
source in a cone with moderate opening angles decrease up to one order of
magnitude the early flux along sightlines oriented away from the direction of
radiation injection but that the reprocessed radiation becomes isotropic
roughly after one lateral diffusion time through the ejecta. We discuss further
applications and guidelines for the use of our novel radiation-hydrodynamics
tool in the context of transient modelling.
