# Early dark energy constraints on growing neutrino quintessence cosmologies

## TL;DR

This paper explores how early dark energy models with a scalar field coupled to neutrinos can be constrained using Planck data, analyzing background evolution with different potentials and functions.

## Contribution

It provides an analytic and numerical analysis of growing neutrino quintessence models, constraining early dark energy contributions with observational data.

## Key findings

- Relaxation of constraints on early dark energy in exponential potentials.
- Constraints on the kinetic function magnitude at early times.
- Analytic solutions for background evolution during radiation and matter domination.

## Abstract

We investigate cosmological models in which dynamical dark energy consists of a scalar field whose present-day value is controlled by a coupling to the neutrino sector. The behaviour of the scalar field depends on three functions: a kinetic function, the scalar field potential, and the scalar field-neutrino coupling function. We present an analytic treatment of the background evolution during radiation- and matter-domination for exponential and inverse power law potentials, and find a relaxation of constraints compared to previous work on the amount of early dark energy in the exponential case. We then carry out a numerical analysis of the background cosmology for both types of potential and various illustrative choices of the kinetic and coupling functions. By applying bounds from Planck on the amount of early dark energy, we are able to constrain the magnitude of the kinetic function at early times.