Singularity-free and cosmologically viable Born-Infeld gravity with scalar matter

TL;DR

This paper demonstrates that Eddington-inspired Born-Infeld gravity with a scalar field can produce nonsingular bouncing cosmologies, effectively replacing the Big Bang singularity, and is consistent with current observational data within tight parameter bounds.

Contribution

It introduces a singularity-free cosmological model within Born-Infeld gravity coupled to scalar matter, with detailed analysis of its properties and observational viability.

Findings

Existence of nonsingular bouncing and loitering solutions.

Model compatible with observations for  \u2264 5 10^{-8} m^2.

New features in cosmological evolution depending on scalar mass.

Abstract

The early Cosmology driven by a single scalar field, both massless and massive, in the context of Eddington-inspired Born-Infeld gravity, is explored. We show the existence of nonsingular solutions of bouncing and loitering type (depending on the sign of the gravitational theory's parameter, $\epsilon$) replacing the Big Bang singularity, and discuss their properties. In addition, in the massive case we find some new features of the cosmological evolution depending on the value of the mass parameter, including asymmetries in the expansion/contraction phases, or a continuous transition between a contracting phase to an expanding one via an intermediate loitering phase. We also provide a combined analysis of cosmic chronometers, standard candles, BAO, and CMB data to constrain the model, finding that for roughly $\vert \epsilon \vert \lesssim 5\cdot 10^{-8} \text{ m}^2$ the model is compatible with the latest observations while successfully removing the Big Bang singularity. This bound is several orders of magnitude stronger than the most stringent constraints currently available in the literature