Anisotropic Dark Energy from a Coupled 2-form Field

Abstract

In this paper, we study the cosmological dynamics of a 2-form field coupled to a cold dark matter component in a Bianchi I background. Using a dynamical system analysis, we show that our model has two attractor solutions corresponding to late-time accelerated universes. These solutions have an important distinction between each other: one is isotropic and the other one is not, i.e. there is a non-zero shear contribution induced by the 2-form field. Due to the coupling in the dark sector, we also obtain a scaling solution where the 2-form field behaves as a pressure-less fluid. For a particular set of parameters and initial conditions, we numerically study the expansion history of the model. We find that the value of the shear at redshift zero is within the current observational bounds, which could be a potential alleviation to the quadrupole anomaly, and that the equation of state of dark energy is exactly -1.Comment: 12 pages, 7 figure