Joakim Rosdahl - April 1, 2016

RHD simulations of stellar radiation feedback in disk galaxies

Radiation feedback is typically implemented using sub-grid recipes in simulations
of galaxies. Very little work has been performed using radiation-hydrodynamics
(RHD), and the importance of radiation in galaxy evolution is unclear. We present
RHD simulations of isolated galaxies with a resolution of ~ 10 pc. Our simulations
include supernova feedback, but also self-consistent treatments of photo-ionisation
heating and of radiation pressure from both direct optical/UV radiation and from
multi-scattered, re-processed IR radiation. Photo-heating smooths and thickens the
disks and suppresses star formation, but decreasingly so with increasing galaxy
mass. Radiation pressure has little effect, but for the IR radiation the impact is
limited by our inability to resolve the high optical depths for which
multi-scattering becomes important. While artificially boosting the IR optical
depths does reduce the star formation, it does so by smoothing the gas rather than
by generating stronger outflows.