A method to determine the evolution history of the mean neutral hydrogen fraction

Mondal, Rajesh, Bharadwaj, Somnath, Iliev, Ilian T, Datta, Kanan K, Majumdar, Suman, Shaw, Abinash K and Sarkar, Anjan K (2019) A method to determine the evolution history of the mean neutral hydrogen fraction. Monthly Notices of the Royal Astronomical Society: Letters, 483 (1). L109-L113. ISSN 1745-3933

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The light-cone (LC) effect imprints the cosmological evolution of the redshifted 21-cm signal Tb (n^,ν) along the frequency axis which is the line of sight (LoS) direction of an observer. The effect is particularly pronounced during the Epoch of Reionization (EoR) when the mean hydrogen neutral fraction x HI (ν) falls rapidly as the universe evolves. The multi-frequency angular power spectrum (MAPS) Cℓ(ν1,ν2) quantifies the entire second-order statistics of Tb (n^,ν) considering both the systematic variation along ν due to the cosmological evolution and also the statistically homogeneous and isotropic fluctuations along all the three spatial directions encoded in n^ and ν. Here we propose a simple model where the systematic frequency (ν1 ,ν2) dependence of C ℓ(ν1,ν2) arises entirely due to the evolution of x ¯ HI (ν). This provides a new method to observationally determine the reionization history. Considering a LC simulation of the EoR 21-cm signal, we use the diagonal elements ν 1 =ν2 of Cℓ(ν1,ν2) to validate our model. We demonstrate that it is possible to recover the reionization history across the entire observational bandwidth provided we have the value x ¯ HI at a single frequency as an external input.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science
Depositing User: Alice Jackson
Date Deposited: 18 Jan 2019 12:27
Last Modified: 18 Jan 2019 12:27
URI: http://srodev.sussex.ac.uk/id/eprint/81342

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