SO Webloquio: Charting the first billion years of our Universe with the Square Kilometre Array

The first billion years witnessed the dawn of the first galaxies, eventually culminating in the final phase change of our Universe: the Epoch of Reionization (EoR). Recent observations allowed us limited glimpses into these epochs, improving our understanding of the timing of the EoR. However, we still do not understand the first galaxies and black holes, the vast majority of which are too faint to be seen directly in the foreseeable future. Luckily, the upcoming decade is set to revolutionise studies of the Cosmic Dawn and EoR, through interferometric observations of the redshifted 21-cm line of neutral hydrogen. Specifically, the Square Kilometer Array (SKA) will map out the first billion years of our Universe: a volume corresponding to the majority of our cosmic lightcone and containing up to 10.000 times the number of modes than are in the CMB! The patterns in these 4D maps are driven by UV and X-ray radiation from the first galaxies, as well as physical cosmology. I will showcase a Bayesian, data-driven framework to understanding astrophysics and cosmology from the cosmic 21-cm signal. By forward-modeling lightcones of the first billion years, we combine existing and future observations of the cosmic dawn and the EoR. I show how the unprecedented size of the upcoming SKA dataset will allow us to recover properties of the (unseen!) first galaxies, including stellar-halo mass relations, ionising escape fraction scalings, X-ray luminosity to star formation rates, relative contributions of Population III and Population II stellar populations, and much more.

19/05/2022 - 12:30
Dr. Andrei Mesinger
Scuola Normale Superiore, Pisa, Italy