Three dimensional Eddington-inspired Born-Infeld gravity: Solutions

Abstract

Three dimensional Eddington-inspired Born--Infeld gravity is studied with the goal of finding new solutions. Beginning with cosmology, we obtain analytical and numerical solutions for the scale factor, a(t), in spatially flat (k=0) and spatially curved (k=+1,-1) Friedmann-Roberston-Walker universes with (i) pressureless dust (P=0) and (ii) perfect fluid (P=\rho/2), as matter sources. When the theory parameter \kappa>0, our cosmological solutions are generically singular (except for the open universe, with a specific condition). On the other hand, for \kappa<0 we do find non-singular cosmologies. We then move on towards finding static, circularly symmetric line elements with matter obeying (i) p=0 and (ii) p=\rho/2. For p=0, the solution found is nonsingular for \kappa<0 with the matter--stress--energy representing inhomogeneous dust. For p=\rho/2 we obtain nonsingular solutions, for all \kappa, and discuss some interesting characteristics of these solutions. Finally, we look at the rather simple p=-\rho case where the solutions are either de Sitter or anti-de Sitter or flat spacetime.