Cosmological implications of a Relic Neutrino Asymmetry

TL;DR

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

Contribution

It analyzes the impact of neutrino degeneracy on cosmological parameters and derives new constraints using observational data.

Findings

Neutrino degeneracy increases the universe's energy density.

Modifies the power spectrum of radiation and matter.

Constraints on neutrino degeneracy and spectral index.

Abstract

We consider some consequences of the presence of a cosmological lepton asymmetry in the form of neutrinos. 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 neutrino degeneracy and on the spectral index in the case of a flat Universe with a cosmological constant.