Supernova Seismology: Gravitational Wave Signatures of Rapidly Rotating Core Collapse

Abstract

Gravitational waves (GW) generated during a core-collapse supernova open a window into the heart of the explosion. At core bounce, progenitors with rapid core rotation rates exhibit a characteristic GW signal which can be used to constrain the properties of the core of the progenitor star. We investigate the dynamics of rapidly rotating core collapse, focusing on hydrodynamic waves generated by the core bounce and the GW spectrum they produce. The centrifugal distortion of the rapidly rotating proto-neutron star (PNS) leads to the generation of axisymmetric quadrupolar oscillations within the PNS and surrounding envelope. Using linear perturbation theory, we estimate the frequencies, amplitudes, damping times, and GW spectra of the oscillations. Our analysis provides a qualitative explanation for several features of the GW spectrum and shows reasonable agreement with nonlinear hydrodynamic simulations, although a few discrepancies due to non-linear/rotational effects are evident. The dominant early postbounce GW signal is produced by the fundamental quadrupolar oscillation mode of the PNS, at a frequency $0.70\mathrm{kHz}\lesssim f\lesssim 0.80\mathrm{kHz}$, whose energy is largely trapped within the PNS and leaks out on a $\sim 10$ ms timescale. Quasi-radial oscillations are not trapped within the PNS and quickly propagate outwards until they steepen into shocks. Both the PNS structure and Coriolis/centrifugal forces have a strong impact on the GW spectrum, and a detection of the GW signal can therefore be used to constrain progenitor properties.

Published in MNRAS

References in corpus (8)

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• Gravitational wave asteroseismology for low-mass neutron stars
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• Pulsar Timing Perturbations from Galactic Gravitational Wave Bursts with Memory
• Estimating the nuclear saturation parameter via low-mass neutron star asteroseismology
• Stability of the protoneutron stars toward black hole formation
• The Yet-Unobserved Multi-Messenger Gravitational-Wave Universe
• Early evolution of newly born proto-neutron stars