Abstract

The filamentary network of intergalactic medium (IGM) gas that gives origin to the “Lyman-alpha forest” encodes information on the physics of structure formation and the early thermodynamics of diffuse baryonic material. I will present results from a massive suite of more than 1080 high-resolution cosmological hydrodynamical simulations run with the Graphics Processing Unit-accelerated code Cholla to study the IGM at high spatial resolution. By varying the amplitude and timing of the photoheating and photoionizing background produced by star-forming galaxies and active galactic nuclei, we can match the observed hydrogen Lyman-alpha forest power spectra and helium Lyman-alpha forest opacity. The available data tightly constrain the photoionization and photoheating history of the IGM , and allow us to infer its thermal history. We then present a new analysis varying the dark matter particle mass to study the consistency between possible free-streaming suppression of the small-scale matter power spectrum and the Lyman-alpha forest, allowing us to constrain cosmological physics from the Lyman-alpha forest while robustly accounting for thermal structure of the IGM .