Gravity seminar - Daniela Cors Seminar

Abstract: At the threshold of black hole formation, a regular and universal structure emerges in spherical symmetry, referred to as critical phenomena in gravitational collapse. The main features of critical collapse have been observed for many matter models. However, whether all of these features emerge without spherical symmetry remains an open question: apparent discrepancies between different studies suggest that the picture of critical collapse beyond spherical symmetry is more subtle. In this talk, the status of critical collapse beyond spherical symmetry in the case of three different matter models will be presented. First, the consensus reached by three independent codes concerning the collapse of gravitational waves in vacuum will be explained. Second, the unresolved case of aspherical deformations of real massless scalar field minimally coupled to general relativity will be described. Last but not least, the latest results concerning aspherical deformations of a massless complex scalar field will be introduced. To the best of our knowledge, the latter include for the first time a tentative explanation of the subtleties of critical phenomena in a symmetry setup where both matter and gravitational waves can influence the collapse dynamics. These results were obtained with the use of two formulation improvements, which proved to be necessary in order to evolve as close to the threshold of collapse as was required to observe the phenomena in question.