Unified framework for Early Dark Energy from $\alpha$-attractors

TL;DR

This paper introduces a unified framework for early dark energy using $oldsymbol{ extalpha}$-attractor models, demonstrating its ability to address the Hubble tension through flexible energy injection profiles confirmed by MCMC analysis.

Contribution

It develops a versatile $oldsymbol{ extalpha}$-attractor based model for early dark energy, enabling various energy injection shapes and showing compatibility with Hubble tension solutions.

Findings

Hubble constant $H_0$ is significantly increased compared to $oldsymbol{ extLambda}$CDM.

The model naturally incorporates the curvature required by data.

MCMC analysis confirms the model's effectiveness in alleviating the Hubble tension.

Abstract

One of the most appealing approaches to ease the Hubble tension is the inclusion of an early dark energy (EDE) component that adds energy to the Universe in a narrow redshift window around the time of recombination and dilutes faster than radiation afterwards. In this paper, we analyze EDE in the framework of $\alpha$-attractor models. As well known, the success in alleviating the Hubble tension crucially depends on the shape of the energy injection. We show how different types of energy injections can be easily obtained, thanks to the freedom in choosing the functional form of the potential inspired by $\alpha$-attractor models. To confirm our intuition we perform an MCMC analysis for three representative cases and find indeed that $H_0$ is significantly larger than in $\Lambda$CDM like in other EDE models. Unlike axion-driven EDE models with super Planckian decay constant, the curvature of EDE models required by the data is natural in the context of recent theoretical developments in $\alpha$-attractors.