Cosmological analogues of the Bartnik-McKinnon solutions

We present a numerical classification of the spherically symmetric, static solutions to the Einstein-Yang-Mills equations with a cosmological constant Λ. We find three qualitatively different classes of configurations, where the solutions in each class are characterized by the value of Λ and the number of nodes, n, of the Yang-Mills amplitude. For sufficiently small, positive values of the cosmological constant, Λ<Λcrit(n), the solutions generalize the Bartnik-McKinnon solitons, which are now surrounded by a cosmological horizon and approach the de Sitter geometry in the asymptotic region. For a discrete set of values Λreg(n)>Λcrit(n), the solutions are topologically three-spheres, the ground state ($n=1$) being the Einstein universe. In the intermediate region, that is, for Λcrit(n)<Λ<Λreg(n), there exists a discrete family of global solutions with an horizon and "finite size."