  We derive estimates for the characteristics of gravitational radiation from
stellar collapse, using recent models of the core-collapse of Chandrasekhar
mass white dwarfs (accretion induced collapse), core-collapse supernovae and
collapsars, and the collapse of very massive stars (~> 300 Msun). We study
gravitational-wave emission mechanisms using several estimation techniques,
including two-dimensional numerical computation of quadrupole wave emission,
estimates of bar-mode strength, estimates of r-mode emission, and estimates of
waves from black hole ringing. We also review the rate at which the relevant
collapses are believed to occur, which has a major impact on their relevance as
astrophysical sources. Although the latest supernova progenitor simulations
produce cores rotating much slower than those used in the past, we find that
bar-mode and r-mode instabilities from core-collapse supernovae remain among
the leading candidate sources for LIGO-II. Accretion induced collapse (AIC) of
a white dwarf could produce gravitational-wave signals similar to those from
core-collapse. In the models that we examine, such collapses are not unstable
to bar modes; we note that models recently examined by Liu and Lindblom, which
have slightly more angular momentum, are certainly unstable to bar formation.
Because AIC events are probably 1,000 times less common than core-collapse
supernovae, the typical AIC event will be much further away, and thus the
observed waves will be much weaker. In the most optimistic circumstances, we
find it may be possible to detect gravitational waves from the collapse of 300
Msun Population III stars.
