The quantitative impact of strong rotation on the amplitudes and frequencies of the postbounce gravitational wave (GW) signal from core-collapse supernovae (CCSNe) is still not fully understood. To study trends in frequencies and amplitudes, and possibly spectacular phenomena like resonant amplification, we perform a series of axisymmetric long-duration magnetohydrodynamic CCSN simulations of a $17M_{\odot }$ progenitor using a finely spaced grid in initial rotation rate from $0.29\mathrm{rad}{\mathrm{s}}^{-1}$ to $3.48\mathrm{rad}{\mathrm{s}}^{-1}$. We find that these rotating models produce GWs at frequencies of up to 3 kHz, higher than in typical nonrotating models in the literature. The high frequencies arise due to small polar radii of rapidly rotating protoneutron stars and stabilization by angular momentum gradients at lower latitude. GW frequencies and amplitudes tend to decrease with faster rotation. Different from two complementary simulations without magnetic fields, the magnetohydrodynamic models are characterized by an absence of $p$-modes above the dominant high-frequency emission band. We find no indication of resonant mode amplification for any rotation rate, although a temporospatial and space-frequency analysis reveals some interesting couplings of quadrupolar motions across the protoneutron star and the gain region. We find that linear mode analysis based on the spherically averaged structure becomes unsuitable in this regime of rapid rotation. Generalized, multidimensional perturbative techniques need to be developed to study the mode structure and mode interaction in the collapse of rapidly rotating massive stars.

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• Gravitational wave sources
• Novae & supernovae
• Supernova remnants
• Astrophysical & cosmological simulations