The gravitational wave signal from core-collapse supernovae

TL;DR

This study analyzes gravitational wave signals from core-collapse supernovae using simulations, identifying key oscillation modes and their dependence on various stellar parameters to aid detection efforts.

Contribution

It systematically characterizes the GW signal features from supernovae and provides a simple frequency fit useful for gravitational wave data analysis.

Findings

Dominant GW signal after ~400ms is the PNS fundamental quadrupole mode.

Between ~200-400ms, the dominant mode is a g-mode with two radial nodes.

The GW frequency depends weakly on progenitor mass, enabling a simple predictive fit.

Abstract

We study gravitational waves (GWs) from a set of two-dimensional multi-group neutrino radiation hydrodynamic simulations of core-collapse supernovae (CCSNe). Our goal is to systematize the current knowledge about the post-bounce CCSN GW signal and recognize the templatable features that could be used by the ground-based laser interferometers. We demonstrate that starting from ~400ms after core bounce the dominant GW signal represents the fundamental quadrupole (l=2) oscillation mode (f-mode) of the proto-neutron star (PNS), which can be accurately reproduced by a linear perturbation analysis of the angle-averaged PNS profile. Before that, in the time interval between ~200 and ~400ms after bounce, the dominant mode has two radial nodes and represents a g-mode. We associate the high-frequency noise in the GW spectrograms above the main signal with p-modes, while below the dominant frequency there is a region with very little power. The collection of models presented here summarizes the dependence of the CCSN GW signal on the progenitor mass, equation of state, many-body corrections to the neutrino opacity, and rotation. Weak dependence of the dominant GW frequency on the progenitor mass motivates us to provide a simple fit for it as a function of time, which can be used as a prior when looking for CCSN candidates in the LIGO data.