The effects of the small-scale behaviour of dark matter power spectrum on CMB spectral distortion

Sarkar, Abir and Sethi, Shiv K and Das, Subinoy (2017) The effects of the small-scale behaviour of dark matter power spectrum on CMB spectral distortion. In: JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (7).

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Abstract

After numerous astronomical and experimental searches, the precise particle nature of dark matter is still unknown. The standard Weakly Interacting Massive Particle(WIMP) dark matter, despite successfully explaining the large-scale features of the universe, has long-standing small-scale issues. The spectral distortion in the Cosmic Microwave Background(CMB) caused by Silk damping in the pre-recombination era allows one to access information on a range of small scales 0.3 Mpc < k < 10(4) Mpc(-1), whose dynamics can be precisely described using linear theory. In this paper, we investigate the possibility of using the Silk damping induced CMB spectral distortion as a probe of the small-scale power. We consider four suggested alternative dark matter candidates-Warm Dark Matter (WDM), Late Forming Dark Matter, Ultra Light Axion dark matter and Charged Decaying Dark Matter; the matter power in all these models deviate significantly from the Lambda CDM model at small scales. We compute the spectral distortion of CMB for these alternative models and compare our results with the Lambda CDM model. We show that the main impact of alternative models is to alter the sub-horizon evolution of the Newtonian potential which affects the late-time behaviour of spectral distortion of CMB. The y-parameter diminishes by a few percent as compared to the Lambda CDM model for a range of parameters of these models: LFDM for formation redshift z(f) = 10(5) (7\textbackslash%); WDM for mass m(wdm) = 1 keV (2\textbackslash%); CHDM for decay redshift z(decay) = 10(5) (5\textbackslash%); ULA for mass m(a) = 10(-24) eV (3\textbackslash%). We also briefly discuss the detectability of this deviation in light of the upcoming CMB experiment PIXIE, which might have the sensitivity to detect this signal from the pre-recombination phase.

Item Type:	Journal Article
Publication:	JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Additional Information:	Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Department/Centre:	Division of Physical & Mathematical Sciences > Astronomy and Astrophysics Programme
Date Deposited:	01 Sep 2017 10:03
Last Modified:	16 Oct 2018 10:06
URI:	http://eprints.iisc.ac.in/id/eprint/57727

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