The quintom model with O(N) symmetry

Abstract

We investigate the quintom model of dark energy in the generalizedcase where the corresponding canonical and phantom fields possessO(N) symmetries. Assuming exponential potentials we find that thisO(N) quintom paradigm exhibits novel properties comparing to the simple canonical and phantomscenarios. In particular, we find that the universe cannot result in a quintessence-type solution withw>−1, even in the cases where the phantom field seems to be irrelevant. On the contrary, thereare always late-time attractors which correspond to accelerating universes withw<−1 and with a recent crossing of the phantom divide, and for a very large area of theparameter space they are the only ones. This is in contrast with the previous simplequintom results, where an accelerating universe is a possible late-time stable solution but itis not guaranteed.