CERN Accelerating science

Article
Report number	arXiv:1209.0247 ; CERN-PH-TH-2012-216 ; LAPTH-038-12
Title	CMB photons shedding light on dark matter
Author(s)	Giesen, Gaelle (IPT, Lausanne) ; Lesgourgues, Julien (IPT, Lausanne ; CERN ; Annecy, LAPTH) ; Audren, Benjamin (IPT, Lausanne) ; Ali-Haïmoud, Yacine (Princeton, Inst. Advanced Study)
Publication	2012
Imprint	04 Sep 2012
Number of pages	35
Note	Comments: 35 pages, 14 figures Comments: 35 pages, 14 figures; version accepted in JCAP after minor revisions
In:	JCAP 12 (2012) 008
DOI	10.1088/1475-7516/2012/12/008
Subject category	Astrophysics and Astronomy
Abstract	The annihilation or decay of Dark Matter (DM) particles could affect the thermal history of the universe and leave an observable signature in Cosmic Microwave Background (CMB) anisotropies. We update constraints on the annihilation rate of DM particles in the smooth cosmological background, using WMAP7 and recent small-scale CMB data. With a systematic analysis based on the Press-Schechter formalism, we also show that DM annihilation in halos at small redshift may explain entirely the reionization patterns observed in the CMB, under reasonable assumptions concerning the concentration and formation redshift of halos. We find that a mixed reionization model based on DM annihilation in halos as well as star formation at a redshift z 6.5 could simultaneously account for CMB observations and satisfy constraints inferred from the Gunn-Peterson effect. However, these models tend to reheat the inter-galactic medium (IGM) well above observational bounds: by including a realistic prior on the IGM temperature at low redshift, we find stronger cosmological bounds on the annihilation cross-section than with the CMB alone.
Copyright/License	Preprint: © 2012-2025 CERN (License: CC-BY-3.0)

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