A new framework for cosmological expansion in a reformulated Newtonian-Like gravity with variable G

TL;DR

This paper introduces a modified Newtonian-like gravity framework with a dynamic gravitational constant, enabling accelerated cosmic expansion and enhanced matter perturbation growth, offering new insights into cosmological modeling.

Contribution

It presents a novel variant of a Newtonian-like gravity theory that maintains Newton's second law and incorporates a variable gravitational constant sourced by a scalar field.

Findings

Accelerated expansion possible in a matter-dominated universe.

Enhanced growth of matter density perturbations.

Dynamic gravitational coupling influences cosmological evolution.

Abstract

A Newtonian-like theory inspired by the Brans-Dicke gravitational Lagrangian has been recently proposed in Ref. arXiv:2009.04434(v4). We propose here a new variant of this theory such that the usual Newtonian second law is preserved. The cosmological solutions are analysed and accelerated background expansion can be obtained even in a pure matter dominated universe. This happens due to the dynamic character of the effective gravitational coupling which is sourced by a time evolving scalar field . We also analyse the matter density perturbations and find they exhibit an enhanced growth in comparison with the usual Newtonian like behavior in Einstein-de Sitter model.