Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction

Understand

We explore scenarios for reionizing the intergalactic medium with low galaxy ionizing photon escape fractions.

• We combine simulation-based halo-mass dependent escape fractions with an extrapolation of the observed galaxy rest-ultraviolet luminosity functions to solve for the reionization history from z=20 to z=4.
• We explore the posterior distributions for key unknown quantities, including the limiting halo mass for star-formation, the ionizing photon production efficiency, and a potential contribution from active galactic nuclei (AGN).
• We marginalize over the allowable parameter space using a Markov Chain Monte Carlo method, finding a solution which satisfies the most model-independent constraints on reionization.