COMPUTING THE DELAYED COLLAPSE OF HOT NEUTRON-STARS TO BLACK-HOLES

We perform dynamical simulations of the delayed collapse of hot neutro n stars to black holes. Using our recently developed code for spherica l collapse in general relativity, we can follow this collapse to compl etion, i.e., until the last fluid elements have approached the event h orizon. Therefore, we can study the very late stages of the collapse a nd determine, for example, the neutrino signature of this event. We ad opt a hot kaon condensate equation of state and model neutrino transpo rt with a relativistic diffusion equation. In our simulations, we evol ve hot neutron stars with masses greater than the maximum mass of cold neutron stars. These stars are initially stabilized by thermal pressu re. However, as the stars emit neutrinos and cool down, they eventuall y reach the onset of instability and catastrophically collapse to blac k holes. We track the entire evolution, from the quasi-static onset of collapse to the final dynamical implosion. This calculation is meant to serve as a prototype for more detailed calculations of delayed coll apse, but nevertheless it does illustrate all the physical features th at we expect to find when more detailed calculations are performed.