Neutralino dark matter as the source of the WMAP haze

Abstract

Previously, it has been argued that the anomalous emission from the region around the Galactic Center observed by WMAP, known as the "WMAP Haze", may be the synchrotron emission from relativistic electrons and positrons produced in dark matter annihilations. In particular, the angular distribution, spectrum, and intensity of the observed emission are consistent with the signal expected to result from a WIMP with an electroweak-scale mass and an annihilation cross section near the value predicted for a thermal relic. In this article, we revisit this signal within the context of supersymmetry, and evaluate the parameter space of the Constrained Minimal Supersymmetric Standard Model (CMSSM). We find that, over much of the supersymmetric parameter space, the lightest neutralino is predicted to possess the properties required to generate the WMAP Haze. In particular, the focus point, A-funnel, and bulk regions typically predict a neutralino with a mass, annihilation cross section, and dominant annihilation modes which are within the range required to produce the observed features of the WMAP Haze. The stau-coannihilation region, in contrast, is disfavored as an explanation for the origin of this signal.

Can the WMAP Haze really be a signature of annihilating neutralino dark matter?

“…Here, we re-evaluate the recent proposal that the WMAP haze may originate from synchrotron emission produced by a distribution of high-energy positrons and electrons resulting from the self-annihilation of supersymmetric neutralino dark matter. What differentiates our study from those past [2,5,6,8,9] is that in addition to using a standard set of templates, designed to model Galactic foreground emission, in a template-based, multilinear fit to the CMB-subtracted WMAP data, we use a by-product of the Gibbs sampling method of CMB parameter estimation as our CMB contribution to the data [10], and compare our results with those calculated using the internal linear combination method (ILC) utilised in previous work [2]. Gibbs sampling is a Monte-Carlo Markov Chain method that generates posterior samples of the signal map, power spectrum, and foreground components.…”

“…The hard spectrum has also led to speculation (see e.g. [5,6,7,8]) that the origin of the haze is more likely to be hard synchrotron foreground emission resulting from a source distinct from that responsible for the softer synchrotron emission commonly associated with Galactic foregrounds. An astrophysical origin of such a hard synchrotron spectrum, such as that produced from a distribution of ultra-relativistic electrons, possibly resulting from supernovae explosions, with a flux large enough to account for the haze, seems difficult to realise [8].…”

Gamma rays from the Galactic center and the WMAP haze

“…While these results our not unique to our dark matter models as compared to those of more massive particles (see e.g. [15,24]), these results show the promise for radio observations to constrain the scenarios of high energy dark matter annihilation such as those shown in [2], and the need for further studies, such as a model for synchrotron emission near the galactic center where the total γ-ray intensity is much better constrained.…”

Explaining the WMAP Haze with Neutralino Dark Matter

“…We refer the interested reader to Caceres & Hooper (2008) for further details, including a more extensive discussion of the supersymmetric parameter space and the regions consistent with being the source of the WMAP Haze, as well as the implications for direct and indirect detection experiments.…”

“…In particular, the lightest neutralino (Goldberg 1983;Ellis et al 1984) is a very attractive and well studied dark matter candidate. Here, we revisit the dark matter interpretation of the WMAP Haze and study the supersymmetric parameter space which leads to a lightest neutralino with the properties required to generate the observed emission, summarizing the results of Caceres & Hooper (2008). In Section 2 we briefly overview the results of Hooper et al (2007), where the dark matter properties required to generate the WMAP Haze were determined.…”