## [astro-ph/0511500] Is cosmology compatible with sterile neutrinos?

 Authors: Scott Dodelson, Alessandro Melchiorri, Anze Slosar Abstract: By combining data from cosmic microwave background (CMB) experiments (including the recent WMAP third year results), large scale structure (LSS) and Lyman-alpha forest observations, we constrain the hypothesis of a fourth, sterile, massive neutrino. For the 3 massless + 1 massive neutrino case we bound the mass of the sterile neutrino to m_s<0.26eV (0.44eV) at 95% (99.9%) c.l.. These results exclude at high significance the sterile neutrino hypothesis as an explanation of the LSND anomaly. We then generalize the analysis to account for active neutrino masses (which tightens the limit to m_s<0.23eV 0.42eV) and the possibility that the sterile abundance is not thermal. In the latter case, the contraints in the (mass, density) plane are non-trivial. For a mass of >1eV or <0.05eV the cosmological energy density in sterile neutrinos is always constrained to be omega_nu <0.003 at 95 c.l.. However, for a sterile neutrino mass of ~0.25eV, omega_nu can be as large as 0.01. [PDF]  [PS]  [BibTex]  [Bookmark]

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Hans Kristian Eriksen
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### [astro-ph/0511500] Is cosmology compatible with sterile neut

Sorry for asking a stupid question, but I have some difficulties interpreting figure 2 in this paper. In particular, what does the black, solid line show?

Thanks -- and again, sorry..

Anze Slosar
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### [astro-ph/0511500] Is cosmology compatible with sterile neut

As already discussed in the e-mail correspondence, the black line is a vanilla 0.3-0.7 model with normalisation that is somewhat low wrt to WMAP best fit - since it is for illustrative purposes only, it doesn't really matter in my view.