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Energy injection in pre-recombination era and EDGES detection

Brahma, N and Sethi, S and Sista, S (2020) Energy injection in pre-recombination era and EDGES detection. In: Journal of Cosmology and Astroparticle Physics, 2020 (12).

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Official URL: https://dx.doi.org/10.1088/1475-7516/2020/12/034


We study the possibility of explaining the recent EDGES detection by an energy injection in the pre-recombination era. Our aim is to show that the residue of this energy injection could give the resultant increase in the energy density at frequencies xe � hν/(kT) ' 10�3, which is needed to explain the EDGES result. We consider two models of energy injection: Gaussian profile with a fixed redshift of injection and radiative decay of a non-relativistic particle. We show that the energy injection should occur in the redshift range z . 4�103 to prevent free-free processes from thermalizing the injected energy. The injected energy should be nearly 200�1000 times the CMB intensity at xe ' 10�3 to obtain the requisite residue. A large fraction of the injected energy gets thermalized and therefore distorts the CMB spectrum. We compute CMB spectral distortion for both the models and show that the fractional change in CMB energy density, ��CMB/�CMB ' 10�6, which might be detectable with the proposed experiment PIXIE. We also outline the implication of our proposed scenario for CMB anisotropies. © 2020 IOP Publishing Ltd and Sissa Medialab.

Item Type: Journal Article
Publication: Journal of Cosmology and Astroparticle Physics
Publisher: IOP Publishing Ltd
Additional Information: Copyright to this article belongs to IOP Publishing Ltd
Department/Centre: UG Programme
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 03 Feb 2021 10:26
Last Modified: 03 Feb 2021 10:26
URI: http://eprints.iisc.ac.in/id/eprint/67833

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