Simulating gravitational collapse is a very active area of numerical astrophysics, and most simulations
also predict the energy and spectral characteristics of the emitted gravitational waves [167].
However, it is still beyond the capabilities of computers to simulate a gravitational collapse event
with all the physics that might be necessary to give reliable predictions: three-dimensional
hydrodynamics, neutrino transport, realistic nuclear physics, magnetic fields, rotation. In fact, it is still
by no means clear why Type II supernovae explode at all: simulations typically have great
difficulty reversing the inflow and producing an explosion with the observed light-curves and
energetics. It may be that the answer lies in some of the physics that has to be oversimplified in
order to be used in current simulations, or in some neutrino physics that we do not yet know,
or in some unexplored hydrodynamic mechanism [277]. In a typical supernova, simulations
suggest that gravitational waves might extract between about 10–7 and 10–5 of the total available
mass-energy [266, 148, 149], and the waves could come off in a burst whose frequency might lie in the
range of
200 – 1000 Hz.
We can use Equation (18) to make a rough estimate of the amplitude, if the emitted energy and
timescale are known. Using representative values for a supernova in our galaxy, lying at 10 kpc, emitting
the energy equivalent of
at a frequency of 1 kHz, and lasting for 1 ms, the received amplitude
would be
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