Traditional large-scale models of reionization usually employ simple deterministic relations between halo mass and luminosity to predict how reionization proceeds. We here examine the impact on modelling reionization of using more detailed models for the ionizing sources as identified within the 100 Mpc/h cosmological hydrodynamic simulation Simba, coupled with post-processed radiative transfer. Comparing with simple (one-to-one) models, the main difference of using Simba sources is the scatter in the relation between dark matter halos and star formation, and hence ionizing emissivity. We find that, at the power spectrum level, the ionization morphology remains mostly unchanged, regardless of the variability in the number of sources or escape fraction. Our results show that simplified models of ionizing sources remain viable to efficiently model the structure of reionization on cosmological scales, although the precise progress of reionization requires accounting for the scatter induced by astrophysical effects.
Reionization with Simba: How much does astrophysics matter in modeling cosmic reionization?, Sultan Hassan, Romeel Davé, Matthew McQuinn, Rachel S. Somerville, Laura C. Keating, Daniel Anglés-Alcázar, Francisco Villaescusa-Navarro, David N. Spergel, submitted to ApJ, arXiv:2109.03840