Published in The First Galaxies, Astrophysics and Space Science Library, Volume 396. ISBN 978-3-642-32361-4. Springer-Verlag Berlin Heidelberg, 2013, p. 45.
http://arxiv.org/abs/1206.0267

For a PDF version of the article, click here.

THE EPOCH OF REIONIZATION

Saleem Zaroubi


Kapteyn Astronomical Institute, Landleven 12, 9747AD Groningen, The Netherlands
and
Physics Department, The Technion, Haifa 32000, Israel


Abstract: The Universe's dark ages end with the formation of the first generation of galaxies. These objects start emitting ultraviolet radiation that carves out ionized regions around them. After a sufficient number of ionizing sources have formed, the ionized fraction of the gas in the Universe rapidly increases until hydrogen becomes fully ionized. This period, during which the cosmic gas went from neutral to ionized, is known as the Universe's Epoch of Reionization . The Epoch of Reionization is related to many fundamental questions in cosmology, such as properties of the first galaxies, physics of (mini-)quasars, formation of very metal-poor stars and a slew of other important research topics in astrophysics. Hence uncovering it will have far reaching implications on the study of structure formation in the early Universe. This chapter reviews the current observational evidence for the occurrence of this epoch, its key theoretical aspects and main characteristics, and finally the various observational probes that promise to uncover it. A special emphasis is put on the redshifted 21 cm probe, the various experiments that are currently being either built or designed, and what we can learn from them about the Epoch of Reionization.


Table of Contents

INTRODUCTION

OBSERVATIONAL EVIDENCE FOR REIONIZATION
The Lyman alpha forest at z ≈ 2.5-6.5
The Thomson Scattering Optical depth for the Cosmic Microwave Background (CMB) Radiation
The Intergalactic Medium at z ltapprox 6
Other Observational Probes

THE REIONIZATION PROCESS

THE REDSHIFTED 21 cm AS A PROBE OF THE EoR
The 21 cm Spin and Brightness Temperatures
The Differential Brightness Temperature
The 21 cm forest at high z

THE REDSHIFTED 21 cm OBSERVATION
Radio Interferometry and the Calibration Problem
Current and Future EoR Experiments
Station configuration and uv coverage
Noise Issues
The Foregrounds

THE STATISTICS OF THE OBSERVED COSMOLOGICAL SIGNAL
The 21 cm Power Spectrum
High order statistics
Cross-correlating the LOFAR-EoR data with other data sets

SUMMARY

REFERENCES

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