The Gravitational-Wave Power Gap in Core-Collapse Supernovae: Insights from 60 Axisymmetric Simulations

TL;DR

This study analyzes gravitational-wave emissions from 60 axisymmetric supernova simulations, revealing a power gap linked to neutron star core properties and exploring interference mechanisms behind it.

Contribution

It provides the first systematic analysis of the gravitational-wave power gap in supernovae and connects it to the physical conditions of the neutron star core.

Findings

The power-gap frequency correlates with the sound speed in the neutron star core.

The power gap can result from destructive interference between oscillation modes and background signals.

The analysis offers insights into matter behavior at extreme densities.

Abstract

We analyse the gravitational-wave emission from 60 two-dimensional core-collapse supernova simulations. The models cover a range of progenitors and equations of state. We focus on the narrow frequency interval in the gravitational-wave spectrum where the emitted power is strongly suppressed (the power gap) and how its central frequency relates to the physical properties of the simulations. We find that the power-gap frequency exhibits strong and systematic correlations with the properties of the inner core of the forming neutron star, for example the sound speed, suggesting that the gap encodes information about the behaviour of matter at extreme densities. We further examine how well several mechanisms proposed in the literature account for the presence and evolution of the gap in our simulations. Finally, we explore a scenario in which the gap arises from destructive interference between a narrow oscillation mode and a broadband background signal, demonstrating that such an interaction can produce a sharp minimum in the emitted gravitational-wave power.