  While low mass, star forming galaxies are often considered as the primary
driver of reionization, their actual contribution to the cosmic ultraviolet
background is still uncertain, mostly because the escape fraction of ionizing
photons is only poorly constrained. Theoretical studies have shown that
efficient supernova feedback is a necessary condition to create paths through
which ionizing radiation can escape into the intergalactic medium. We
investigate the possibility that accreting supermassive black holes in early
dwarf galaxies may provide additional feedback and enhance the leakage of
ionizing radiation. We use a series of high resolution cosmological radiation
hydrodynamics simulations where we isolate the different sources of feedback.
We find that supernova feedback prevents the growth of the black hole, thus
quenching its associated feedback. Even in cases where the black hole can grow,
the structure of the interstellar medium is strongly dominated by supernova
feedback. We conclude that, in the dwarf galaxy regime, supermassive black
holes do not appear to play a significant role in enhancing the escape fraction
and in contributing to the early UV background.
