  We study gravitational waves (GWs) from a set of two-dimensional multi-group
neutrino radiation hydrodynamic simulations of core-collapse supernovae
(CCSNe). Our goal is to systematize the current knowledge about the post-bounce
CCSN GW signal and recognize the templatable features that could be used by the
ground-based laser interferometers. We demonstrate that starting from ~400ms
after core bounce the dominant GW signal represents the fundamental quadrupole
(l=2) oscillation mode (f-mode) of the proto-neutron star (PNS), which can be
accurately reproduced by a linear perturbation analysis of the angle-averaged
PNS profile. Before that, in the time interval between ~200 and ~400ms after
bounce, the dominant mode has two radial nodes and represents a g-mode. We
associate the high-frequency noise in the GW spectrograms above the main signal
with p-modes, while below the dominant frequency there is a region with very
little power. The collection of models presented here summarizes the dependence
of the CCSN GW signal on the progenitor mass, equation of state, many-body
corrections to the neutrino opacity, and rotation. Weak dependence of the
dominant GW frequency on the progenitor mass motivates us to provide a simple
fit for it as a function of time, which can be used as a prior when looking for
CCSN candidates in the LIGO data.
