Evolution of Differentially Rotating Supermassive Stars to the Onset of Bar Instability

Thermal emission from a rotating, supermassive star will cause the configuration to contract slowly and spin up. If internal viscosity and magnetic fields 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 instability, which may trigger the growth of nonaxisymmetric bars. This scenario will lead to the generation of long-wavelength gravitational waves, which could be detectable by future space-based laser interferometers like the Laser Interferometer Space Antenna.