Matt McQuinn

History of the Intergalactic Medium Thermal History

The thermal history of the intergalactic medium (IGM) is governed by the relatively simple physics of photoheating and cooling, and can be constrained using measurements from the Lyman-alpha forest. Over the past decade, these measurements have become much more precise. Unexpectedly, important theoretical advances have also emerged -- particularly regarding the initial heating from ionization fronts (found to depend primarily on their velocity) and the patchy nature of this heating. These insights, along with progress in modeling ionizing background fluctuations, motivated several groups to develop more sophisticated models and simulations, which were then compared to Lyman-alpha forest data at z = 5-6. A consensus picture has since emerged that reionization ends late, below z = 6.

While much of this talk will highlight the past decade of developments, I will also present an exciting new one:  photo-evaporative heating from reionization may drive the entire IGM to turbulence, as it does in some of our highest-resolution simulations.  If so, this turbulence should grow magnetic fields everywhere, explaining the lower limits on intergalactic magnetic fields inferred from TeV blazars.