Chameleon dark energy can resolve the Hubble tension

TL;DR

This paper proposes a novel late-time inhomogeneous model involving a chameleon field to resolve the Hubble tension by locally increasing the expansion rate in overdense regions.

Contribution

It introduces a new mechanism where a chameleon field coupled to matter overdensities can locally elevate the Hubble constant, addressing the tension between local and CMB measurements.

Findings

A region with 20% overdensity can resolve the Hubble tension.

Chameleon fields can be trapped at higher potential energy densities.

The model aligns local Hubble measurements with large-scale structure data.

Abstract

Values of the Hubble constant between the direct measurements from various independent local observations and that inferred from the cosmic microwave background with the $\Lambda$-cold-dark-matter model are in tension with persistent significance. We propose a late-time inhomogeneous resolution suggesting that a chameleon field coupled to a local overdensity of matter could be trapped at a higher potential energy density as an effective cosmological constant driving the local expansion rate faster than that of the background with lower matter density. We illustrate this mechanism in a toy model in which a region with only $20\%$ overdensity of matter is sufficient to resolve the Hubble tension, and the Hubble constant measured by the local distance ladders could be accommodated by the chameleon coupled to the observed overdensities from the large-scale structure surveys.