Late time acceleration due to generic modification of gravity and Hubble tension

TL;DR

This paper explores a modified gravity scenario where late-time cosmic acceleration arises from an interaction between dark matter and baryons, potentially alleviating the Hubble tension by causing a phantom crossing and increasing the expansion rate at late times.

Contribution

It introduces a novel modified gravity framework with disformal transformations that produce late-time acceleration and reduce Hubble tension, differing from standard models.

Findings

Hubble tension is significantly reduced in the model.

The universe's age remains consistent with observations.

Late-time dynamics exhibit phantom crossing due to effective fluid.

Abstract

We consider a scenario of modified gravity, which is generic to late-time acceleration, namely, acceleration in the Jordan frame and no acceleration in the Einstein frame. The possibility is realized by assuming an interaction between dark matter and the baryonic component in the Einstein frame which is removed by going to the Jordan frame using a disformal transformation giving rise to an exotic effective fluid responsible for causing phantom crossing at late times. In this scenario, past evolution is not distinguished from $\Lambda$CDM but late time dynamics is generically different due to the presence of phantom crossing that causes a monotonous increase in the expansion rate giving rise to distinctive late-time cosmic feature. The latter can play a crucial role in addressing the tension between the observed value of Hubble parameter by CMB (Cosmic Microwave Background) measurements and the local observations. We demonstrate that the Hubble tension significantly reduces in the scenario under consideration for the chosen scale factor parametrizations. The estimated age of the universe in the model is well within the observational bounds in the low and high red-shift regimes.