Relic neutrino asymmetry, CMB and large-scale structure

TL;DR

This paper explores how a relic neutrino asymmetry affects the universe's energy density and structure, providing constraints based on cosmic microwave background and large-scale structure observations.

Contribution

It analyzes the impact of neutrino lepton asymmetry on cosmological parameters and derives new constraints from observational data.

Findings

Relic neutrino degeneracy increases the universe's energy density.

Neutrino asymmetry modifies the radiation and matter power spectra.

Constraints on neutrino degeneracy and spectral index are obtained from observations.

Abstract

We consider some consequences of the presence of a cosmological lepton asymmetry in the form of neutrinos. A relic neutrino degeneracy enhances the contribution of massive neutrinos to the present energy density of the Universe, and modifies the power spectrum of radiation and matter. Comparing with current observations of cosmic microwave background anisotropies and large scale structure, we derive some constraints on the relic neutrino degeneracy and on the spectral index in the case of a flat Universe with a cosmological constant.