Abstract Details

Name: Janakee Raste
Affiliation: Raman Research Institute, Bangalore
Conference ID: ASI2017_1256
Title : Analytically Modelling Early Phase of EoR
Authors and Co-Authors : Shiv Sethi, Raman Research Institute
Abstract Type : Oral
Abstract Category : General Relativity and Cosmology
Abstract : Epoch of Reionization is one of the most important events in the history of the universe. During this time, stars and galaxies, which formed in large scale collapsed structures, ionized and heated the medium surrounding them. Ly-alpha, X-ray and ultraviolet were three of the most important components of the radiation emitted by these collapsed sources. To study the EoR, redshifted 21 cm signal, emitted or absorbed by neutral hydrogen (HI), is one of the most important probes. This signal is affected by the spectrum of the radiation and details of structure formation. Therefore, it is important to examine various models of EoR analytically, before we can detect the 21 cm signal. We analytically model the early phase of EoR, which allows us to investigate the impact of different modelling parameters on 21 cm signal and its 2-point correlation. We use excursion set formalism to generate number distribution of ionized bubbles at any redshift and generate temperature profiles around these bubbles by examining the effects of Ly-alpha and X-ray on the medium. We use geometric and probabilistic arguments to calculate 2-point correlation of the 21 cm Brightness temperature and contrast it against simplistic models where complete or no heating is assumed. We also try to examine the effect of temperature correlation on the total 21 cm correlation and the global history of reionization. This method can be applied to calculate and compare correlation for various reionization and heating histories during the early phase of reionization when ionization fraction is small and bubbles do not overlap.