Modeling the Intergalactic Medium during the Epoch of Reionization

Abstract

A major goal of observational and theoretical cosmology is to observe the largely unexplored time period in the history of our universe when the first galaxies form, and to interpret these measurements. Early galaxies dramatically impacted the gas around them in the surrounding intergalactic medium (IGM) by photoionzing the gas during the Epoch of Reionization (EoR). This epoch likely spanned an extended stretch in cosmic time: ionized regions formed and grew around early generations of galaxies, gradually filling a larger and larger fraction of the volume of the universe. At some time -- thus far uncertain, but within the first billion years or so after the big bang -- essentially the entire volume of the universe became filled with ionized gas. The properties of the IGM provide valuable information regarding the formation time and nature of early galaxy populations, and many approaches for studying the first luminous sources are hence based on measurements of the surrounding intergalactic gas. The prospects for improved reionization-era observations of the IGM and early galaxy populations over the next decade are outstanding. Motivated by this, we review the current state of models of the IGM during reionization. We focus on a few key aspects of reionization-era phenomenology and describe: the redshift evolution of the volume-averaged ionization fraction, the properties of the sources and sinks of ionizing photons, along with models describing the spatial variations in the ionization fraction, the ultraviolet radiation field, the temperature of the IGM, and the gas density distribution.

Book Chapter in "Understanding the Epoch of Cosmic Reionization: Challenges and Progress", Springer International Publishing, Ed. Andrei Mesinger, ISBN 978-3-319-21956-1

References in corpus (24)

• A luminous quasar at a redshift of z = 7.085
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• UV Luminosity Functions at z~4, 5, and 6 from the HUDF and other Deep HST ACS Fields: Evolution and Star Formation History
• Efficient Simulations of Early Structure Formation and Reionization
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The morphology of HII regions during reionization
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• The Global 21 Centimeter Background from High Redshifts
• HeII Reionization and its Effect on the IGM
• Studying Reionization with Ly-alpha Emitters
• Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
• Radiative transfer simulations of cosmic reionization I: methodology and initial results
• Simulating Cosmic Reionization at Large Scales II: the 21-cm Emission Features and Statistical Signals
• Accelerated Evolution of Ly$\alpha$ Luminosity Function at $\text{z}\gtrsim 7$ Revealed by the Subaru Ultra-Deep Survey for Ly$\alpha$ Emitters at $\text{z}=7.3$
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• Through Thick and Thin - HI Absorption in Cosmological Simulations
• Imprint of Inhomogeneous Hydrogen Reionization on the Temperature Distribution of the Intergalactic Medium
• Quasar Proximity Zones and Patchy Reionization
• Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization
• Higher Order Contributions to the 21 cm Power Spectrum
• Probing the Neutral Fraction of the IGM with GRBs during the Epoch of Reionization
• On Modeling and Measuring the Temperature of the z~5 IGM
• How to Search for Islands of Neutral Hydrogen in the $z\sim 5.5$ IGM
• CMBPol Mission Concept Study: Reionization Science with the Cosmic Microwave Background

Cited by in corpus (6)

• Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries
• The Aurora radiation-hydrodynamical simulations of reionization: calibration and first results
• The Implications of a Pre-reionization 21 cm Absorption Signal for Fuzzy Dark Matter
• Signatures of metal-free star formation in Planck 2015 Polarization Data
• First study of reionization in the Planck 2015 normalized closed $\Lambda$CDM inflation model
• First study of reionization in tilted flat and untilted non-flat dynamical dark energy inflation models