Inflationary cosmology with Chaplygin gas in Palatini formalism

TL;DR

This paper proposes a modified gravity model with Chaplygin gas that aligns well with current data, offers an internal inflationary mechanism, and suggests a bounce replaces the traditional Big Bang singularity.

Contribution

It introduces a Palatini gravity model with quadratic Starobinsky term and Chaplygin gas, unifying late-time acceleration and early inflation within a single framework.

Findings

Astronomical data favors negative quadratic coupling parameter.

The model predicts a bounce instead of a Big Bang singularity.

The approach provides a unified description of inflation and dark energy.

Abstract

We present a simple generalisation of the $\Lambda$CDM model which on the one hand reaches very good agreement with the present day experimental data and provides an internal inflationary mechanism on the other hand. It is based on Palatini modified gravity with quadratic Starobinsky term and generalized Chaplygin gas as a matter source providing, besides a current accelerated expansion, the epoch of endogenous inflation driven by type III freeze singularity. It follows from our statistical analysis that astronomical data favors negative value of the parameter coupling quadratic term into Einstein-Hilbert Lagrangian and as a consequence the bounce instead of initial Big-Bang singularity is preferred.