Born-Infeld cosmology with scalar Born-Infeld matter

TL;DR

This paper explores cosmological models within Eddington-inspired Born-Infeld gravity using a scalar Born-Infeld matter field, revealing solutions with de Sitter expansion and bounces, and fitting supernova data comparable to Lambda-CDM.

Contribution

It introduces analytical cosmological solutions in Born-Infeld gravity with scalar matter, highlighting their features and observational viability, especially for positive ta.

Findings

For ta>0, solutions exhibit de Sitter-like expansion at early and late times.

For ta<0, solutions include a bounce but are observationally disfavored.

Late-time solutions fit supernova data as well as mbda-CDM.

Abstract

Cosmology in Eddington-inspired Born-Infeld gravity is investigated using a scalar Born-Infeld field (e.g. tachyon condensate) as matter. In this way, both in the gravity and matter sectors we have Born-Infeld-like structures characterized by their actions and via two separate constants, $\kappa$ and $\alpha_T^2$ respectively. With a particular choice of the form of $\dot{\phi}$ (the time derivative of the Born-Infeld scalar), analytical cosmological solutions are found. Thereafter, we explore some of the unique features of the corresponding cosmological spacetimes. For $\kappa>0$, our solution has a de Sitter-like expansion both at early and late times, with an intermediate deceleration sandwiched between the accelerating phases. On the other hand, when $\kappa<0$, the initial de Sitter phase is replaced by a bounce. Our solutions, at late time, fit well with available supernova data-- a fact we demonstrate explicitly. The estimated properties of the Universe obtained from the fitting of the $\kappa>0$ solution, are as good as in $\Lambda$CDM cosmology. However, the $\kappa<0$ solution has to be discarded due to the occurrence of a bounce at an unacceptably low redshift.