Cosmological evolution from modified Bekenstein entropy law

TL;DR

This paper investigates a modified entropy-based gravity model, revealing self-accelerating cosmological solutions with implications for early and late universe acceleration, while constraining deviations from general relativity through scalar perturbation stability.

Contribution

It introduces a cosmological model based on quantum-corrected Bekenstein entropy with detailed analysis of its solutions and stability constraints.

Findings

Existence of self-accelerating solutions approaching de Sitter space.

No solutions indicating a primordial bounce.

Scalar perturbation stability constrains deviations from general relativity.

Abstract

We study the dynamics of the homogeneous and isotropic cosmological background in the recently proposed ``quantum phenomenological gravitational dynamics'', characterised by logarithmic corrections to the Bekenstein entropy. We show that the model admits a family of solutions that are self-accelerating both at early and late times: they approach de Sitter in the future and admit a past attractor corresponding to an inflationary acceleration era. On the other hand, there are no solutions corresponding to a primordial bounce. We also show that asking scalar perturbations to be unaffected by instabilities on observable scales puts stringent constraints on the deviations from general relativity encoded by the model.