Inaugural Lecture by Charlotte Mason

Title: Chasing Cosmic Dawn and Reionization

Abstract: There is a missing chapter in our Universe’s history. We cannot yet see the “Cosmic Dawn”, when the very first stars and galaxies lit up the Universe. These objects are too faint and rare, and their light is redshifted beyond the reach of our current telescopes. However, we believe these first galaxies fundamentally altered their surroundings - driving the Universe’s final phase transition by transforming cool, atomic, intergalactic hydrogen to a hot, but diffuse, plasma. I will describe how this “Reionization" process depends on the interplay between the poorly understood astrophysics of galaxy formation (e.g. massive star formation and feedback processes) and the unknown nature of dark matter on small scales, and thus constraining how Reionization happened is key to understanding the underlying physics. I will describe how we can look back in time to this period by observing the distant Universe, in particular by using atomic hydrogen transitions. I will present our current understanding of Reionization and Cosmic Dawn inferred from these observations and theoretical models, and discuss the prospects of future facilities, such as the upcoming James Webb Space Telescope and new radio telescopes, to fill in our cosmic origin story.

Simulation image by M. Alverez et al.
                                          Simulation image by M. Alverez et al.