Title:	Observational Constraints on Global 21-cm Signals from the Epoch of Reionization
Authors:	Singh, Saurabh
Thesis Advisor:	Subrahmanyan, Ravi
Subject:	Astronomy and Astrophysics
Issue Date:	May-2018
Publisher:	Raman Research Institute, Bangalore
Citation:	Ph.D. Thesis, Indian Institute of Science, Bangalore, 2018
Abstract:	Cosmic Dawn (CD), beginning with first light from the first stars and ultra-faint galaxies, and Epoch of Reionization (EoR), resulting in almost complete reionization of the primordial gas, marks an important period in the cosmic evolution of baryons. There is considerable uncertainty and limited observational constraints on the evolution of thermal and ionization state of the intergalactic medium (IGM) in this period as well as on the nature of the first sources of light that caused the transformation. One of the most promising probes of these epochs is the rest-frame global 21-cm signal of neutral hydrogen (HI) produced by the intergalactic medium (IGM) prior to the end of the EoR at z 6. The intensity of the signal is tied to the star formation history as well as to the ionization and thermal histories of the IGM. Hence, its measurement will bracket astrophysical properties of the first UV and X-ray sources including the ionizing efficiency of first stars and quasars, luminosity and spectra of the first population of black holes, and properties of dark matter particles. At present these properties are poorly understood allowing for a large variety of plausible 21-cm spectra.
Description:	Open Access
URI:	http://hdl.handle.net/2289/7547
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Appears in Collections:	Theses (A&A)

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