Anisotropic emission of neutrino and gravitational-wave signals from rapidly rotating core-collapse supernovae

Abstract

We present analysis of neutrino and GW signals based on three-dimensional (3D) core-collapse supernova simulations of a rapidly rotating 27 $M_{\odot}$ star. We find a new neutrino signature that is produced by a lighthouse effect where the spinning of strong neutrino emission regions around the rotational axis leads to quasi-periodic modulation in the neutrino signal. Depending on the observer's viewing angle, the time modulation will be clearly detectable in IceCube and the future Hyper-Kamiokande. The GW emission is also anisotropic where the GW signal is emitted, as previously identified, most strongly toward the equator at rotating core-collapse and bounce, and the non-axisymmetric instabilities in the postbounce phase lead to stronger GW emission toward the spin axis. We show that these GW signals can be a target of LIGO-class detectors for a Galactic event. The origin of the postbounce GW emission naturally explains why the peak GW frequency is about twice of the neutrino modulation frequency. We point out that the simultaneous detection of the rotation-induced neutrino and GW signatures could provide a smoking-gun signature of a rapidly rotating proto-neutron star at the birth.