Early Universe and the Epoch of Reionization

Principal Investigator: Valentina D'Odorico


  • Early Universe
  • Structures in the Universe

Abstract: The first billion years of the Universe define the current frontier of modern cosmology, both observationally and theoretically. During this time, the first stars and galaxies assembled from the primordial gas, and the atomic hydrogen permeating the early Universe became ionised. The epoch of reionisation (EoR) represents a major phase transition in cosmic history, which impacted almost every baryon in the Universe. Recent results from independent, state-of-the-art probes of the reionization process (Planck collaboration 2018, arXiv:1807.06209; Kulkarni et al. 2019; Konno et al. 2018; Pentericci et al. 2018) suggest that the EoR was underway at z~9 and lasted below z~6. Thanks to the increasing number of bright quasars detected at z ≥ 6 (e.g. Bañados et al. 2016; Wang et al. 2018 arXiv:1810.11926) it is now possible to pierce into the EoR. High-z bright quasars can be used both as signposts of big massive galaxies, whose properties can be studied in emissions and as background sources to study the intervening medium in absorption along the line of sight. The nature of the first stars (so called PopIII stars), responsible for the reionization process, can be studied both locally, looking for the oldest and most metal-poor stars in our galaxy and in its close companions, and at the highest redshifts, determining the chemical abundances of the absorption systems in quasar spectra. We propose a line of research to investigate these topics using state-of-the-art, multiband observations of high-z quasars and predictions from hydro-dynamical and semi-analytical models.

Description: See attached document.