Effect of helium on hydrogen reionization

In the early universe, the birth of the first sources produced ample amounts of ultraviolet radiation capable of converting the intergalactic medium from neutral to ionized, a phase known as the epoch of reionization. The timing, duration, and cause of reionization is still not well understood. However, over the past decade, research into this has exploded with the advent of moment based radiative transfer simulations. It has been found that a late and rapid reionization model leads to the best fit to the current observations. However, these results were derived without the presence of helium in the simulation models, and this is the problem I worked on at TIFR. In my talk, I will discuss the implementation of helium into ATON, a fast GPU based radiative transfer program, the cosmological simulations (160 cMPc/h) we ran, the effects of helium on the observables of the Lyman-alpha forest data, and what the simulation suite can further be used for.