Cosmology of neutrinos and extra light particles after WMAP3
Abstract
We study how present data probe standard and non-standard properties of neutrinos and the possible existence of new light particles, freely-streaming or interacting, among themselves or with neutrinos. Our results include: sum m_nu < 0.40 eV at 99.9% C.L.; that extra massless particles have abundance Delta N_nu = 2 pm 1 if freely-streaming and Delta N_nu = 0 pm 1.3 if interacting; that 3 interacting neutrinos are disfavored at about 4 sigma. We investigate the robustness of our results by fitting to different sub-sets of data. We developed our own cosmological computational tools, somewhat different from the standard ones.
Cite
@article{arxiv.astro-ph/0607086,
title = {Cosmology of neutrinos and extra light particles after WMAP3},
author = {Marco Cirelli and Alessandro Strumia},
journal= {arXiv preprint arXiv:astro-ph/0607086},
year = {2009}
}
Comments
18 pages, 8 figures. Added in v2: an explicit comparison of our code with CAMB, some clarifications on the statistical analysis and some references. Matches version published in JCAP