The Indirect Influence of Quasars on Reionization
  The exact role of quasars during the Epoch of Reionization remains uncertain.
With consensus leaning towards quasars producing a negligible amount of
ionizing photons, we pose an alternate question: Can quasars indirectly
contribute to reionization by allowing ionizing photons from stars to escape
more easily? Using the Semi-Analytic Galaxy Evolution model to evolve a galaxy
population through cosmic time, we construct an idealized scenario in which the
escape fraction of stellar ionizing photons ($f_\mathrm{esc}$) is boosted
following quasar wind events, potentially for several dynamical times. We find
that under this scenario, the mean value of $f_\mathrm{esc}$ as a function of
galaxy stellar mass peaks for intermediate mass galaxies. This mass dependence
will have consequences for the 21cm power spectrum, enhancing power at small
scales and suppressing it at large scales. This hints that whilst quasars may
not directly contribute to the ionizing photon budget, they could influence
reionization indirectly by altering the topology of ionized regions.
