Critical Phenomena in the Aspherical Collapse of Radiation Fluids

We study critical phenomena in the gravitational collapse of radiation fluids. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical solution in spherically symmetric collapse, and study the approach to this critical solution in the absence of spherical symmetry. Our simulations are preformed with an unconstrained evolution code, implemented in spherical polar coordinates, and adopting "moving-puncture" coordinates.