Magnetic bags and black holes

We discuss gravitational magnetic bags, i.e., clusters of large numbers of monopoles in the presence of gravitational effects. Physics depends on the dimensionless ratio between the vev of the Higgs field at infinity and the Planck mass. We solve the equations for the gravitational bags, and study the transition from monopole to black hole. The critical coupling for this transition is upsilon(cr) = root pi/(4 root G), and it is larger than that of a single 't Hooft-Polyakov monopole. We investigate the black hole limit in detail. (C) 2010 Elsevier B.V. All rights reserved.