Choose timezone
Your profile timezone:
Powered by Indico
v3.3.3
Speaker: Andrei Mesinger, Scuola Normale Superiore
Title: Charting the first billion years of our Universe with the cosmic 21-cm signal
Abstract:
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 forceable future. Luckily, the upcoming decade is set to revolutionize 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 will demonstrate this framework on preliminary data from the SKA-precursor instrument: Hydrogen Epoch of Reionization Arrays (HERA). Preliminary upper limits from HERA, when combined with galaxy and EoR observations, allow us to constrain the thermal history of the Universe as well as the X-ray luminosities of high mass X-ray binaries that are likely responsible.. Finally, I will show how the unprecedented size of the upcoming SKA dataset will allows us to recover properties of the (unseen!) first galaxies, and potentially also the properties of dark matter.