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Jeremiah W. Murphy, Christian D. Ott, Adam Burrows
Submitted to the Astrophysical Journal, arXiv:0907.4762
- Gravitational Wave Signal Data -
Abstract
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Using a suite of progenitor models (12, 15, 20 and 40 solar masses) and neutrino luminosities in
two-dimensional (2D) simulations, we
investigate the gravitational-wave (GW) emission from postbounce
phases of core-collapse supernovae (CCSNe).
We characterize the matter GW signatures of prompt convection, steady-state
convection, the standing accretion shock instability (SASI) , and
asymmetric explosions. The characteristic GW frequency evolves from
~100 Hz just after bounce to ~300-400 Hz, with higher
frequencies corresponding to higher mass progenitors and models that
take longer to explode by the neutrino mechanism. After vigorous convective/SASI motions
start, the GW strain amplitude increases roughly tenfold and shows features
that strongly correlate with downdrafts striking the protoneutron star (PNS)
``surface.'' During
explosion, the high frequency signal wanes and is replaced by a
strong low frequency, ~10s of Hz, signal that reveals the general
morphology of the explosion (i.e. prolate, oblate, or spherical).
However, ``seeing'' the explosion morphology requires direct observations of the
GW strain amplitude at low frequencies, and current and near-future GW detectors
are sensitive to GW power at frequencies > ~50 Hz. In practice, the signature of explosion for these detectors
will be the abrupt reduction of detectable GW emission.
For the stages before explosion, we propose a model for the source of
GW emission that explains the characteristic
frequencies and amplitudes. Downdrafts of the postshock-convection/SASI region strike the PNS ``surface'' with large speeds
and are decelerated by buoyancy forces. We find that the GW
amplitude is set by the magnitude of deceleration and, by extension,
the downdraft's speed. However, the characteristic frequencies are primarily
independent of these speeds (and turnover timescales), but are set by
the deceleration timescale, which is in turn set by the buoyancy
frequency (Brunt-Väisälä frequency) at the lower boundary of postshock convection.
Since the buoyancy frequency is determined by global and local properties,
the GW characteristic frequencies are dependent upon a combination of the dense-matter
equation of state (EOS) and the specifics that determine the gradients
at the boundary, including the mass-accretion-rate history, the EOS at
subnuclear densities, and neutrino transport. In summary, detection
of GWs from CCSNe may reveal details of the core structure and
dynamics of the explosion mechanism.
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Below we provide gravitational wave signature data for our model set discussed in this paper.
For each model we compute and make available here the gravitational wave emissions from matter motions (on the entire grid) via the slow-motion, weak-field quadrupole approximation. Details on the extraction formalism can be found in the paper.
All models are nonrotating. The gravitational-wave emission is due to prompt and neutrino-driven postbounce
convection and to the standing-accretion-shock instability. Emission characteristics are discussed at length
in the paper. A recent review on the overall gravitational-wave signature of core-collapse supernovae can be
found in Ott 2009.
A quantitative summary of the gravitational-wave results can be found here (PNG) or here (PDF). All data files are in gzipped plain text ASCII format with two columns: time (in seconds) and h_+ at an assumed source distance of 10 kpc and as seen by an equatorial observer.
Please let us know if you have any questions or comments concerning the waveform data:  or 
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