Cosmology from a new non-conservative gravity

TL;DR

This paper introduces a cosmological model based on a non-conservative gravity theory where dissipative effects emerge from a geometric origin via a least action principle, affecting cosmic evolution and structure formation.

Contribution

It presents a novel cosmological model derived from a non-conservative gravity theory with dissipation arising from a geometric least action principle, and derives background and perturbation equations.

Findings

Dark energy emerges from geometric dissipative effects.

First-order perturbation equations for matter fluctuations are derived.

The model offers a new perspective on cosmic acceleration and structure growth.

Abstract

In this paper we present a cosmological model arising from a non-conservative gravitational theory proposed in [PRD 95, 101501(R) (2017)]. The novel feature where comparing with previous implementations of dissipative effects in gravity is the possible arising of such phenomena from a least action principle, so they are of a purely geometric nature. We derive the dynamical equations describing the behaviour of the cosmic background, considering a single fluid model composed by pressureles matter, whereas the dark energy is conceived as an outcome of the "geometric" dissipative process emerging in the model. Besides, adopting the synchronous gauge we obtain the first-order perturbative equations which shall describe the evolution of the matter perturbations within the linear regime.