6533b829fe1ef96bd128990b
RESEARCH PRODUCT
Do observations prove that cosmological neutrinos are thermally distributed?
A. CuocoGianpiero ManganoSergio PastorJulien Lesgourguessubject
PhysicsNuclear and High Energy PhysicsParticle physicsAstrophysics::High Energy Astrophysical Phenomenamedia_common.quotation_subjectCosmic microwave backgroundDark matterAstrophysics (astro-ph)FOS: Physical sciencesFísicaAstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsUniverseCosmologyCosmic neutrino backgroundHigh Energy Physics - PhenomenologyHigh Energy Physics - Phenomenology (hep-ph)Big Bang nucleosynthesisNucleosynthesisNeutrinomedia_commondescription
It is usually assumed that relic neutrinos possess a Fermi-Dirac distribution, acquired during thermal equilibrium in the Early Universe. However, various mechanisms could introduce strong distortions in this distribution. We perform a Bayesian likelihood analysis including the first moments of the three active neutrino distributions as free parameters, and show that current cosmological observations of light element abundances, Cosmic Microwave Background (CMB) anisotropies and Large Scale Structures (LSS) are compatible with very large deviations from the standard picture. We also calculate the bounds on non-thermal distortions which can be expected from future observations, and stress that CMB and LSS data alone will not be sensitive enough in order to distinguish between non-thermal distortions in the neutrino sector and extra relativistic degrees of freedom. This degeneracy could be removed by additional constraints from primordial nucleosynthesis or independent neutrino mass scale measurements.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2005-02-22 |