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 ; Sarkar, Anjan K (2018) 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 1745-3925

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Official URL: http://doi.org/10.1093/mnrasl/sly226

Related URL: http://dx.doi.org/10.1093/mnrasl/sly226

Abstract

The light-cone (LC) effect imprints the cosmological evolution of the redshifted 21-cm signal Tb(n^,ν) along the frequency axis that 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 multifrequency angular power spectrum 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 Cℓ(ν1,ν2) arises entirely due to the evolution of x¯HI(ν)⁠. This provides a new method to observationally determine the reionization history. Considering an LC simulation of the EoR 21-cm signal, we use the diagonal elements ν1 = 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
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Deposited On:09 Apr 2021 04:02
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