Gravitational Waves from Stellar Collapse: Correlations to Explosion Asymmetries

The collapse of massive stars produces not only observable outbursts across the entire electromagnetic spectrum but, for Galactic (or near-Galactic) supernovae, detectable signals for ground-based neutrino and gravitational-wave detectors. Gravitational waves and neutrinos provide the only means to study the actual engine behind the optical outbursts: the collapsed stellar core. While the neutrinos are most sensitive to details of the equation of state, gravitational waves provide a means to study the mass asymmetries in this central core. We present gravitational-wave signals from a series of three-dimensional core-collapse simulations with asymmetries derived from initial perturbations caused by precollapse convection, core rotation, and low-mode convection in the explosion engine itself. A Galactic supernovae will allow us to differentiate these different sources of asymmetry. Combining this signal with other observations of the supernova, from neutrinos to gamma-rays to the compact remnant, dramatically increases the predictive power of the gravitational-wave signal. We conclude with a discussion of the gravitational-wave signal arising from collapsars, the leading engine for long-duration gamma-ray bursts.