Andrei Mesinger (Astronomy) - Scuola Normale Superiore
Title: Inferring the properties of the first X-ray binaries with the cosmic 21-cm signal
Abstract: The birth of the first stars, black holes and galaxies heralded the end of the cosmic Dark Ages and the beginning of the Cosmic Dawn. The light from these objects heated and ionized almost every atom in existence, culminating in the Epoch of Reionization (EoR): the final major phase change of the Universe. This final frontier of astrophysical cosmology is undergoing a transition from an observationally-starved epoch to a "Big Data" field. This process is set to culminate with upcoming observations of the redshifted 21-cm line: providing a 3D map of the first billion years of our Universe. The patterns in these 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, forward-modeling framework to understanding astrophysics and cosmology from the Cosmic Dawn. I will demonstrate how preliminary 21-cm data from the Hydrogen Epoch of Reionization Array (HERA), when combined with other EoR and galaxy observations, already constrain the heating and ionization history of the Universe. High mass X-ray binaries (HMXBs) are mostly likely responsible for heating the intergalactic medium before the EoR, and current HERA limits imply that the first HMXBs were more luminous than local ones, consistent with theoretical arguments based on binary evolution in low metallicity environments. Finally, I will show forecasts how future 21-cm detections will allow us to infer in detail the population-averaged properties and SEDs of these astrophysical black holes.
Bio: Andrei Mesinger is an Associate Professor of Cosmology at the Scuola Normale Superiore (SNS) in Pisa. His research interests are first light, reionization, cosmic 21-cm high-redshift galaxies, modeling techniques, machine learning and Bayesian inference. He received his PhD at Columbia University in 2006, and subsequently held postdoctoral fellowships at Yale University and Princeton University, before moving to SNS. His research was awarded the Hubble prize fellowship in 2008, and the Starting Grant Award from the European Research Council in 2015. He has written over 140 peer-reviewed publications (h-index 51), and edited two books. He is deeply involved in current efforts to detect the cosmic 21-cm signal, and is the current co-chair of the Epoch of Reionization and Cosmic Dawn Science Working Group for the Square Kilometer Array telescope, as well as being an executive board member of the Hydrogen Epoch of Reionization Array collaboration.