Observing the epoch of reionization and dark ages with redshifted 21-cm hydrogen line

Shukla, Hemant (2015) Observing the epoch of reionization and dark ages with redshifted 21-cm hydrogen line. Doctoral thesis (PhD), University of Sussex.

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The billion years subsequent to the Big Bang pose the next challenging frontier for
precision cosmology. The concordant cosmological model, ΔCDM, propounds that during
this period, the dark matter gravitationally shepherds the baryonic matter to form the
primordial large-scale structures. This era is termed the Dark Ages (DA). The following
era, the Epoch of Reionization (EoR), leads to the formation of the first stars and galaxies
that reionize the permeating neutral hydrogen. The linear polarization of the cosmic
background radiation and the Gunn-Peterson troughs in quasar absorption spectra provide
indirect evidence for the EoR. Currently, there is no observational evidence for the DA.

While state-of-the-art radio telescope arrays, Low Frequency Array (LOFAR) and Square
Kilometre Array (SKA), propose various strategies to observe the early phases of
the Universe, the advanced simulations employing high-performance computing (HPC)
methodologies continue to play significant role in constraining various models based upon
limited observational data. Despite a wide range of research, there is no end-to-end
simulation solution available to quantifiably address the observational challenges due
to statistical and systematic errors including foregrounds, ionosphere, polarization, RFI,
instrument stability, and directional dependent gains.

This research consolidates the cutting-edge simulation solutions, Cube-P3M, C2-Ray,
and MeqTrees, to build an HPC prototype pipeline entitled, Simulating Interferometry
Measurements (SIM). To establish and validate the efficacy of the SIM pipeline, the
research builds a theoretical framework of two science drivers, viz., the presence of Lymanlimit absorbers and measuring non-Gaussianity from the 21-cm data. Thereafter, using the LOFAR and SKA telescope configurations, the SIM generates data visibility cubes
with direction dependent and independent propagation effects. Finally, SIM extracts the original signal through standard techniques exploring the parametric phase-space. Results are presented herein.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy > QB0980 Cosmogony. Cosmology
Depositing User: Library Cataloguing
Date Deposited: 16 Jun 2015 09:56
Last Modified: 28 Sep 2015 14:50
URI: http://sro.sussex.ac.uk/id/eprint/54270

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