The Physics and Early History of the Intergalactic Medium

Abstract

The intergalactic medium - the cosmic gas that fills the great spaces between the galaxies - is affected by processes ranging from quantum fluctuations in the very early universe to radiative emission from newly-formed stars. This gives the intergalactic medium a dual role as a powerful probe both of fundamental physics and of astrophysics. The heading of fundamental physics includes conditions in the very early universe and basic cosmological parameters. The astrophysics refers to chapters of the long cosmic history of stars and galaxies that are being revealed through the effects of stellar feedback on the cosmic gas. This review describes the physics of the intergalactic medium, focusing on recent theoretical and observational developments in understanding early cosmic history. In particular, radiation from the earliest generation of stars is thought to have transformed the universe, turning the surrounding atoms into free electrons and ions. Knowing exactly when and how the reionization process happened is a primary goal of cosmologists, because this would tell us when the early stars and black holes formed and in what kinds of galaxies. Cosmic reionization is beginning to be understood with the help of theoretical models and computer simulations. A wide variety of instruments currently under design will probe the first sources of light during an epoch in cosmic history that has been largely unexplored so far. The new observations and the challenges for theoretical models and numerical simulations will motivate intense work in this field over the coming decade. (abridged)

36 pages, 17 figures, Reports on Progress in Physics (Invited Review), revised version

References in corpus (2)

• The CMBR fluctuations from HI perturbations prior to reionization
• Nonlinear clustering during the cosmic Dark Ages and its effect on the 21-cm background from minihalos

Cited by in corpus (17)

• Baryon Acoustic Oscillation Intensity Mapping as a Test of Dark Energy
• Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
• Evolution of the 21 cm signal throughout cosmic history
• Possibility of Precise Measurement of the Cosmological Power Spectrum With a Dedicated 21cm Survey After Reionization
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• The minimum stellar metallicity observable in the Galaxy
• How Dark Matter Reionized The Universe
• Signatures of reionization on Lyman alpha emitters
• Cosmological constraints from 21cm surveys after reionization
• Primordial Globular Clusters, X-Ray Binaries & Cosmological Reionisation
• Detectability of CMB tensor B modes via delensing with weak lensing galaxy surveys
• Primordial black holes in the Dark Ages: Observational prospects for future 21cm surveys
• Planck and reionization history: a model selection view
• Intergalactic baryon-rich regions at high redshift
• Let there be Light: the Emergence of Structure out of the Dark Ages in the Early Universe
• The Infancy of Cosmic Reionization
• Is a Classical Language Adequate in Assessing the Detectability of the Redshifted 21cm Signal from the Early Universe?