Related papers: Probing patchy reionization through tau-21cm corre…
Observations with radio arrays that target the 21-cm signal originating from the early Universe suffer from a variety of systematic effects. An important class of these are reflections and spurious couplings between antennas. We apply a…
The process of reionization is now believed to have proceeded in an orchestrated manner beginning with UV photons emitted by high redshift galaxies containing a large fraction of Population III stars carving out ionised regions around them.…
Cross-correlating 21cm with known cosmic signals will be invaluable proof of the cosmic origin of the first 21cm detections. As some of the widest fields available, comprising thousands of sources with reasonably known redshifts,…
We show that the epoch(s) of reionization when the ionization fraction of the universe is about half can be determined by correlating Cosmic Microwave Background (CMB) temperature maps with 21-cm line maps at degree scales ($l\sim 100$).…
As a result of our limited data on reionization, the total optical depth for electron scattering, $\tau$, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the…
Detecting redshifted 21cm emission from neutral hydrogen in the early Universe promises to give direct constraints on the epoch of reionization (EoR). It will, though, be very challenging to extract the cosmological signal (CS) from…
Measurement of the spatial distribution of neutral hydrogen via the redshifted 21 cm line promises to revolutionize our knowledge of the epoch of reionization and the first galaxies, and may provide a powerful new tool for observational…
The epoch of reionization is one of the least known chapters in the evolutionary history of the Universe. This thesis investigates two major approaches to unveil the reionization history of the Universe using HI 21-cm maps.The most…
Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal-to-noise, limited by…
We present constraints on the reionization optical depth, $\tau$, obtained using several independent methods. First, we perform a non-parametric reconstruction of the reionization history, using Lyman-$\alpha$ constraints on the evolution…
We investigate a number of potential foregrounds for an ambitious goal of future radio telescopes such as the Square Kilometer Array (SKA) and Low Frequency Array (LOFAR): spatial tomography of neutral gas at high redshift in 21cm emission.…
Measuring the properties of the intergalactic medium (IGM) and sources during the Epoch of Reionization (EoR) is of immense importance. We explore the prospects of probing the IGM and sources through redshifted 21-cm observations of…
We study cross-correlations of the kinetic Sunyaev-Zel'dovich effect (kSZ) and 21 cm signals during the epoch of reionisation (EoR) to measure the effects of patchy reionisation. Since the kSZ effect is proportional to the line-of-sight…
We re-examine the role of collisions in decoupling the HI 21-cm spin temperature from the cosmic microwave background (CMB). The cross section for de-exciting the 21-cm trasition in collisions with free electrons is more than 10 times…
We present predictions for two statistical measures of the hydrogen reionization process at high redshift. The first statistic is the number of neutral segments identified in spectra of high redshift QSOs as a function of their length. The…
In this paper, we explore the constraints on the reionization history that are provided by current observations of the Lyman-alpha forest and the CMB. Rather than using a particular semi-analytic model, we take the novel approach of…
The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation (EoR). This has led to the construction of low-frequency radio interferometric arrays, such as the Hydrogen Epoch of…
Detection and analysis of the cosmic 21 cm signal of neutral hydrogen has long been considered the most promising route towards exploration of the Epoch of Reionization (EoR). 21CMMC, a Markov Chain Monte Carlo sampler of the semi-numerical…
Detecting and characterizing individual ionized bubbles during the Epoch of Reionization (EoR) using the redshifted HI 21-cm signal provides a direct probe of the early ionizing sources and the intergalactic medium. We develop and validate…
21cm-galaxy cross-correlation will play a key role in confirming the cosmological 21cm signal. We investigate which survey configurations detect the 21cm-LAE cross-correlation signal, and assess its ability to distinguish reionisation…