Inhomogeneous HeII reionization in Hydrodynamic Simulations

Understand

The reionization of the second electron of helium shapes the physical state of intergalactic gas at redshifts between 2 < z < 5.

• Because performing full in situ radiative transfer in hydrodynamic simulations is computationally expensive for large volumes, the physics of HeII reionization is often approximated by a uniform UV background model that does not capture the patchiness of reionization.
• We have devised a model that implements the effects of HeII reionization using semi-analytic calculations of the thermal state of intergalactic gas-- a way to bypass a full radiative transfer simulation while still realizing the physics of HeII reionization that affects observables such as the Lyman alpha forest.
• Here we present a publicly-available code that flexibly models inhomogeneous HeII reionization in simulations at a negligible computational cost.