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

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posted on 2023-06-08, 20:59 authored by Hemant Shukla
The billion years subsequent to the Big Bang pose the next challenging frontier for precision cosmology. The concordant cosmological model, ?CDM, 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.


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University of Sussex

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