Low-Frequency Gravitational Waves in Three-Dimensional Core-Collapse Supernova Models

TL;DR

This work analyzes low-frequency gravitational-wave signals from three nonrotating Chimera 3D core-collapse supernova models, focusing on memory-like emission arising from both fluid motion and anisotropic neutrino radiation. By deriving the TT-formulated fluid memory and a linearized GR treatment of neutrino memory, the authors show that neutrino anisotropy often dominates the $<250$ Hz band, with anisotropy well below $5\%$ yet producing comparable strains to fluid signals. They develop a logistic template to characterize the memory ramp-up via a ramp frequency $k$ and final amplitude $L$, and demonstrate that a template bank can enable matched-filtering searches across observer orientations. Reconstruction tests in real interferometric data reveal fluid-memory features are recoverable while neutrino-memory remains challenging to isolate with current pipelines, though future detectors (CE/ET/LISA) offer promising detection prospects for Galactic events and long-lived memories. Overall, the study provides a concrete framework for templated, multi-channel CCSN GW searches and underscores the potential of low-frequency memory as a multimessenger probe of core-collapse dynamics.

Abstract

We discuss the low-frequency gravitational wave signals from three state-of-the-art three-dimensional core-collapse supernova models produced with the \textsc{Chimera} supernova code. We provide a detailed derivation of the gravitational wave signal sourced from the anisotropic emission of neutrinos and provide the total (fluid sourced and neutrino sourced) gravitational waves signal generated in our models. We discuss the templatablity of this low-frequency signal, which is useful for future work involving matched filtering for signal detection and parameter estimation.

Figures (19)

• Figure 1: Gravitational waves sourced from the fluid motions in our core-collapse supernova models. The top row shows the plus polarization at the source. The bottom row shows the cross polarization at the source. Each column shows the different signals at a specific observer orientation with respect to the source frame. Note the significantly lower amplitude signal from the D9.6-3D model, which indicates a more spherical explosion.
• Figure 2: The spherical polar frame of the source is shown in black, where the radiation in a solid angle $(\phi,\theta)$ being emitted from the source is shown in red. We superimpose two example observer frames, given by $(\beta,\alpha)$. The frame delineated in blue corresponds to the observer frame assuming the observer is along the source's z-axis. The frame delineated in green corresponds to the observer frame assuming the observer is along the source's x-axis.
• Figure 3: Energy luminosity of the neutrinos from D9.6-3D (top), D15-3D (middle), and D25-3D (bottom). The luminosity for each evolved species separately is delineated by color, and the total neutrino luminosity is delineated in black.
• Figure 4: Observer--source relative orientation, reproduced from 2012AA...537A..63M.
• Figure 5: The anisotropy (left) and strain (right) for the plus (solid) and cross (dashed and y-shifted) polarizations for the polar axis and the D9.6-3D model. The contribution of each species independently is delineated by color, and the total is delineated in black.