Theoretical approaches for studying the epoch of reionization and Dark Matter annihilation

Tue, September 15, 2015

We explore the properties of the intergalactic medium (IGM) during the epoch of reionization numerically. Our simulation models fully self-consistently all relevant physics, from radiative transfer to gas dynamics and star formation, in volumes of up to 40 co-moving Mpc, and with spatial resolution approaching 100 pc in physical units. The achieved resolution allows us to consider the IGM to be fully resolved. We propose a type of phase diagram which helps to visually analyze the ionization and recombination rates, and calculate the clumping factor. 

We then test the analytical models of reionization and show how they relate to the numerical models. In particular we outline the weak points of the existing analytical models, and how they can be improved. Using our findings of the IGM properties in numerical simulations, we build an analytic model which closely mimics the numerical simulations and reproduces the neutral hydrogen power spectrum. 

Lastly, we take a look at an exotic scenario of reionization, in which the Dark Matter annihilation has a significant impact on the global ionization fraction. We explore what constraints can be placed on Dark Matter from current and future observations of the epoch of reionization.