SPECIAL SEMINAR: "Modeling the UV-Background in Cosmological Hydrodynamical Simulations"

 

 

 

The ultraviolet background (UVB) governs the ionization state of intergalactic gas and plays a key role in its thermal evolution. In current state of the art cosmological hydrodynamical simulations the UVB has to be implemented as a uniform and isotropic set of photoionization and photoheating rates provided by self-consistent UVB models (e.g. Faucher-Giguere et al. 2009, Haardt & Madau 2012). I will show that simulations using these self-consistent UVB models give different ionization and thermal histories that the ones claimed, ionizing and heating the Universe much earlier than they should. I will discuss the implications of this problem in the study of the intergalactic medium properties and the formation and evolution of galaxies. I will also present a new method that I have developed to solve this problem and that allows to build consistent UVB models with different ionization and thermal histories.