Neutrino Masses from Cosmological Probes in Interacting Neutrino Dark-Energy Models

TL;DR

This paper explores how interactions between massive neutrinos and a scalar field could explain late-time cosmic acceleration, providing formulas, analyzing data constraints, and discussing stability issues in these dark energy models.

Contribution

It introduces explicit linear perturbation formulas for neutrino-dark energy interactions and constrains neutrino masses within these models using current cosmological data.

Findings

Neutrino mass sum constrained to <0.45 eV at 1σ

Scalar field dynamics affect cosmic microwave background anisotropies

Neutrinos are stable against density fluctuations in these models

Abstract

We investigate whether interaction between massive neutrinos and quintessence scalar field is the origin of the late time accelerated expansion of the universe. We present explicit formulas of the cosmological linear perturbation theory in the neutrinos probes of dark-energy model, and calculate cosmic microwave background anisotropies and matter power spectra. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for a varying effective equation of states: $\omega_{eff}(z)$ goes down -1. We consider several types of scalar field potential and put constraints on the coupling parameter between neutrinos and dark energy. By combining data from cosmic microwave background (CMB) experiments including the WMAP 3-year results, large scale structure with 2dFGRS data sets, we constrain the hypothesis of massive neutrinos in the mass-varying neutrino scenario. Assuming the flatness of the universe, the constraint we can derive from the current observation is $\sum m_{\nu} < 0.45$ eV at 1$\sigma$ (0.87 eV at 2$\sigma$) confidence level for the sum over three species of neutrinos. The dynamics of scalar field and the impact of scalar field perturbations on cosmic microwave background anisotropies are discussed. We also discuss on the instability issue of the our model and confirm that neutrinos are stable against the density fluctuation.