Primordial Neutrinos, Cosmological Perturbations in Interacting Dark-Energy Model: CMB and LSS

TL;DR

This paper develops cosmological perturbation theory for models where neutrino masses vary due to interactions with dark energy, analyzing their effects on CMB and LSS, and constraining model parameters with current data.

Contribution

It introduces a framework for analyzing neutrino-dark energy interactions with variable neutrino masses and provides observational constraints on the coupling parameter.

Findings

Neutrino mass sum constrained to < 0.87 eV at 95% CL

Model stability considerations discussed

Impact of scattering terms on Boltzmann equations analyzed

Abstract

We present cosmological perturbation theory in neutrinos probe interacting dark-energy models, and calculate cosmic microwave background anisotropies and matter power spectrum. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for the cosmic acceleration today. We consider several types of scalar field potentials and put constraints on the coupling parameter between neutrinos and dark energy. Assuming the flatness of the universe, the constraint we can derive from the current observation is $\sum m_{\nu} < 0.87 eV$ at the 95 % confidence level for the sum over three species of neutrinos. We also discuss on the stability issue of the our model and on the impact of the scattering term in Boltzmann equation from the mass-varying neutrinos.