“A fierce new challenge: unveiling the connection between the first galaxies and reionization”
The formation of the first galaxies in the Universe is the new frontier of both galaxy formation and reionization studies. The James Webb Space Telescope has already revolutionized our ability to observe primeval galaxies, and soon 21cm intensity mapping experiments will allow us to directly witness the reionization process. This unique moment in history creates a fierce new challenge, namely to simultaneously understand in a unique and coherent picture the processes of galaxy formation and reionization, and – crucially – their connection. The latter, in particular, has escaped past numerical efforts. In this talk I will present the first results on this front from an years-long effort geared toward achieving such comprehensive picture, culminated in the Thesan suite of cosmological radiation-magneto-hydrodynamical simulations. I will briefly introduce the features of Thesan, highlighting the successes and failures of its physical model. Thesan produces realistic galaxy populations thanks to state-of-the-art physics, including self-consistent dust production+destruction and radiation transport. I will then show how Thesan can, for the first time, reproduce the connection between IGM and galaxies, as measured from the modulation of the Lyman-alpha flux around galaxies. Finally, I will chart the way forward towards and even deeper understanding of the emergence of the first structures in the Universe.