Cosmic acceleration sourced by modification of gravity without extra degrees of freedom

TL;DR

This paper explores a modified gravity scenario where late-time cosmic acceleration arises from dark matter-baryonic matter coupling without dark energy or extra degrees of freedom, constrained by observational data.

Contribution

It introduces a disformal coupling model that explains cosmic acceleration without dark energy or additional fields, and constrains this model using astrophysical and cosmological data.

Findings

Model can produce late-time acceleration in Jordan frame

Constraints from globular cluster age data and cosmological observations

Possible phantom acceleration behavior in certain parameter regions

Abstract

In this paper, we investigate a scenario in which late time cosmic acceleration might arise due to coupling between dark matter and baryonic matter without resorting to dark energy or large scale modification of gravity associated with extra degrees of freedom. The scenario can give rise to late time acceleration in Jordan frame and no acceleration in Einstein frame - \textit{generic modification of gravity} caused by disformal coupling. Using a simple parametrization of the coupling function, in maximally disformal case, we constrain the model parameters by using the age constraints due to globular cluster data. We also obtain observational constraints on the parameters using $H(z)+SNIa+BAO$ data sets. In this case, we distinguish between phantom and non phantom acceleration and show that the model can give rise to phantom behavior in a narrow region of parameter space.