2.5 Going further
The AIC scenario is generally discussed in terms of the collapse of an accreting white dwarf to a neutron
star. However, Shibata, Baumgarte, and Shapiro have examined the collapse of a rotating, supramassive
neutron star to a black hole [224]. Such supramassive neutron stars (with masses greater than the
maximum mass for a nonrotating neutron star) could be formed and pushed to collapse via accretion from a
binary companion. They performed 3D, fully general relativistic hydrodynamics simulations of
uniformly rotating neutron stars. Dynamical non-axisymmetric instabilities (such as the bar-mode)
did not have time to grow in their simulations prior to black hole formation. Differentially
rotating neutron star progenitors could have higher values of
than the uniformly rotating
models used in this study and may be susceptible to non-axisymmetric instabilities on a shorter
timescale.