The 21-cm Line as a Probe of Reionization

Abstract

One of the most exciting probes of the early phases of structure formation and reionization is the spin-flip line of neutral hydrogen, with a rest wavelength of 21 cm. This chapter introduces the physics of this transition and the astrophysical parameters upon which it depends, including discussions of the radiation fields that permeate the intergalactic medium that fix the brightness of this transition. We describe the critical points in the evolution of the 21-cm background and focus on the sky-averaged brightness and the power spectrum as representative measurements. Finally, we include a discussion of observations and the challenges they face in the near future.

Book chapter in "Understanding the Epoch of Cosmic Reionization: Challenges and Progress", Springer International Publishing, Ed. Andrei Mesinger, ISBN 978-3-319-21956-1 (33 pages, 8 figures)

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Cited by in corpus (29)

• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• Bayesian constraints on the global 21-cm signal from the Cosmic Dawn
• The Evolution of 21-cm Structure (EOS): public, large-scale simulations of Cosmic Dawn and Reionization
• The Impact of Modeling Errors on Interferometer Calibration for 21 cm Power Spectra
• A General Bayesian Framework for Foreground Modelling and Chromaticity Correction for Global 21cm Experiments
• Comparing Foreground Removal Techniques for Recovery of the LOFAR-EoR 21cm Power Spectrum
• A fresh look into the interacting dark matter scenario
• Understanding the HERA Phase I receiver system with simulations and its impact on the detectability of the EoR delay power spectrum
• Separating the EoR Signal with a Convolutional Denoising Autoencoder: A Deep-learning-based Method
• Probing the effects of primordial black holes on 21-cm EDGES signal along with interacting dark energy and dark matter - baryon scattering
• Calibration and 21-cm Power Spectrum Estimation in the Presence of Antenna Beam Variations
• Informing antenna design for sky-averaged 21-cm experiments using a simulated Bayesian data analysis pipeline
• Simulations of Galactic polarized synchrotron emission for Epoch of Reionization observations
• Design of the New Wideband Vivaldi Feed for the HERA Radio-Telescope Phase II
• A Bayesian Calibration Framework for EDGES
• Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1
• Inferring the properties of the sources of reionization using the morphological spectra of the ionized regions
• Exploring the evolution of Reionisation using a wavelet transform and the light cone effect
• Measuring HERA's primary beam in-situ: methodology and first results
• Global 21-cm brightness temperature in viscous dark energy models
• Contribution of Radio Halos to the Foreground for SKA EoR Experiments
• Redundant interferometric calibration as a complex optimization problem
• Contribution of Galactic free-free emission to the foreground for EoR signal in SKA experiments
• Understanding spectral artefacts in SKA-LOW 21-cm cosmology experiments: the impact of cable reflections
• The Impact of ionization Morphology and X-ray Heating on the Cosmological 21cm Skew Spectrum
• Strategy for mitigation of systematics for EoR experiments with the Murchison Widefield Array
• Astrophysical uncertainties challenge 21-cm forecasts: A primordial black hole case study
• Establishing a relationship between the cosmological 21 cm power spectrum and interferometric closure phases
• A Monte Carlo Implementation of Galactic Free-Free Emission for the EoR Foreground Models