Rotating black holes, closed timelike curves, thermodynamics, and the enhancon mechanism

We reconsider supersymmetric five dimensional rotating charged black holes and their description in terms of D-branes. By wrapping some of the branes on K3, we are able to explore the role of the enhancon mechanism in this system. We verify that enhancon loci protect the black hole from violations of the second law of thermodynamics which would have been achieved by the addition of certain D-brane charges. The same charges can potentially result in the formation of closed timelike curves by adding them to holes initially free of them, and so the enhancon mechanism forbids this as well. Although this latter observation is encouraging, it is noted that this mechanism alone does not eliminate closed timelike curves from these systems, but is in accord with earlier suggestions that they may not be manufactured, in this context, by physical processes