Evolution of differentially rotating supermassive stars to the onset of bar instability

Thermal emission from a rotating, supermassive star will cause the configur ation to contract slowly and spin up. If internal viscosity and magnetic fi elds are sufficiently weak, the contracting star will rotate differentially . For each of the six initial angular momentum distributions considered, a cooling supermassive star will likely encounter the dynamical bar mode inst ability, which may trigger the growth of nonaxisymmetric bars. This scenari o will lead to the generation of long-wavelength gravitational waves, which could be detectable by future space-based laser interferometers like the L aser Interferometer Space Antenna.