Critical behavior and universality in gravitational collapse of a charged scalar field

We summarize results from a study of spherically symmetric collapse of a charged (complex) massless scalar field. We present an analytic argument which conjectures the generalization of the mass-scaling relation and echoing phenomena, originally discovered by Choptuik, for the charged case. Furthermore, we study the behavior of the self-similar critical solution under external perturbations - addition of a cosmological constant ii and under a variation of the charge coupling constant e. Finally, we study the scaling relation of the black-hole charge. Using an analytic argument, we conjecture that black holes of infinitesimal mass are neutral or obey the relation Q(BH)much less than M(BH). We verify our predictions with numerical results.