Off-Shoots

Currently, a great deal of interest attaches to the production of gravitational waves (GW) by compact objects. Two possible sources of GW kicked around are:

• The coalescence of neutron star binary systems (New & Tohline). A burst of GW emission is produced as the neutron stars merge. The detection of GW from merging binaries depends sensitively upon knowing the wave form of the GW burst (because it is a transient event). Without prior knowledge of the waveform, it would be difficult to detect such brusts. It is thus crucial that numerical simulations produce accurate wave forms. In principle, one would like to follow merging systems from the Newtonian limit to merger. This, however, requires an inordinate amount of computer time. People therefore start with close systems (almost touching) and then let 'em rip. Even then, things are tough and there not many relativistic simulations around. A nagging problem in these works is the correct set of intitial conditions for the neutron stars in the binary.

• The collapse of rapidly rotating stellar cores. The bar mode could lead to GW emission in such collapses (cf. Rampp, Muller, & Ruffert 1998; Smith, Houser & Centrella 1996). Further, after the initial pulse of GW, the bar which forms, although dynamically stable, is secularly unstable to GRR. The bar could then become a steady source of GW as it secularly evolves to a stable configuration (cf. Imamura et al. 1985, Imamura et al. 1995).

Formation of Kerr Black Holes

• The bar mode instability could lead to something known as a modified Fizzler mechansim through which rapidly rotating black holes (nearly maximal Kerr black holes) could form. Many black holes found in transient x-ray binary systems are rotating near their maximal rates. The formation of such rapidly rotating black holes through ordinary binary evolution is difficult to understand. Perhaps fizzled supernova outbursts in rapidly rotating cores of massive stars is the explantaion.