Born-Infeld cosmology with scalar Born-Infeld matter

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, $κ$ and $α_T^2$ respectively. With a particular choice of the form of $\dotϕ$ (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 $κ>0$, 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 $κ<0$, 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 $κ>0$ solution, are as good as in $Λ$CDM cosmology. However, the $κ<0$ solution has to be discarded due to the occurrence of a bounce at an unacceptably low redshift.

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