2009
Author(s): Popa, LA (Popa, L. A.); Stefanescu, P (Stefanescu, P.); Vasile, A (Vasile, A.)
Source: ROMANIAN REPORTS IN PHYSICS Volume: 61 Issue: 3 Pages: 531-545 Published Date: 2009
Abstract: By using most of the present Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) measurements and the Big Bang Nucleosynthesis (BBN) constraints on the primordial helium abundance, Y-p, we set bounds on the radiation content of the Universe and neutrino properties. We consider lepton asymmetric cosmological models and we find that present CMB and LSS data constraint the neutrino degeneracy parameter at xi(v) (and consequently the lepton asymmetry of the neutrino background L-v), Delta N-oth(eff) the variation of the relativistic degrees of freedom due to possible other physical processes that occurred between BBN and structure formation epoch, the contribution to the effective number of relativistic neutrino species Delta N-eff and Y-p (2-sigma errors), better than older datasets or CMB data alone and the standard value of Y-p 0.24, relaxing the stringent BBN constraint on the neutrino degeneracy parameter.
We forecast that the CMB temperature and polarization maps observed with high angular resolutions and sensitivity by the future Planck Mission will constraint Y-p in agreement with its most stringent limits given by the BBN and also the neutrino degeneracy parameter, not excluding the possibility of larger lepton asymmetry. This work has been done on behalf of Planck-LFI activities.
Accession Number: WOS:000271172200018