Speaker
Description
Title: Near-critical spacetimes of collapsing axisymmetric gravitational waves
Abstract: The process of creating a black hole by collapsing gravitational waves is a long-studied problem in numerical relativity, particularly as a pure-gravity model of critical collapse. One of the reasons for the rather slow progress in understanding critical collapse of gravitational waves is that usual hyperbolic slicing conditions, such as the 1+log slicing, break down in this context. We show that once the breakdown of coordinate conditions is overcome, we can study several families of axisymmetric asymptotically flat initial data families, for which a strength parameter can be fine-tuned between dispersal into empty space and collapse into a black hole, similarly to the well-known discovery by Choptuik. We find that such near-critical spacetimes exhibit behavior similar to scalar-field collapse: for different families of initial data, we observe universal “echoes” represented by approximate scaled copies of the same spacetime region. In contrast to the very regular behavior observed in the collapse of spherically symmetric massless
