Constraining the gravitational-wave emission of core-collapse supernovae with ground-based detectors

TL;DR

This paper addresses the challenge of constraining the gravitational-wave emission from core-collapse supernovae (CCSNe) by analyzing the gravitational-wave background (GWB) using cross-correlation data from Advanced LIGO and Virgo during the O3 run. It models the GWB as a CCSNe component with a Gaussian energy spectrum superposed with a CBC background, and performs a Bayesian analysis to place 95% credibility upper limits on the average GW energy per CCSN, accounting for CBC contamination. The authors report upper limits of $E_{\\mathrm{GW}} < 1.1\times 10^{-2} M_ c^2$ (CCSNe only) and $E_{\\mathrm{GW}} < 9.9\times 10^{-3} M_ c^2$ (CCSNe+CBC) under Prior I, and $E_{\\mathrm{GW}} < 3.3\times 10^{-2} M_ c^2$ and $3.2\times 10^{-2} M_ c^2$ under Prior II, significantly improving upon previous initial-LIGO bounds. The study also forecasts detection prospects for third-generation detectors: ET and CE could detect the GWB if $E_{\\mathrm{GW}} \gtrsim 10^{-4} M_ c^2$ and detect a single CCSN event if $E_{\\mathrm{GW}} \gtrsim 10^{-5} M_ c^2$, with sensitivity strongly depending on the spectral peak and bandwidth. Overall, single-event searches are expected to precede GWB detections, and the results provide astrophysically informative constraints on CCSN GW emission for current and future detectors.

Abstract

A gravitational-wave background (GWB) arising from the superposition of numerous unresolved gravitational-wave signals has yet to be detected. Potential contributing sources to such a background include compact binary coalescences (CBCs) and core-collapse supernovae (CCSNe). In this work, we place upper limits on the gravitational-wave energy emitted by CCSNe using cross-correlation measurements made with Advanced LIGO and Advanced Virgo detectors during their third observing run (O3). Specifically, we obtain a $95\%$ credibility upper limit of $0.01~ {M_\odot c^2}$ while accounting for the contribution from CBC sources to a GWB. This result improves on previous constraint obtained from initial LIGO data by approximately two orders of magnitude. We also explore the detection prospects of third-generation ground-based detectors such as the Einstein Telescope and Cosmic Explorer for both individual CCSNe events and the GWB. Our results show that single events are likely to be detected prior to the GWB.

Figures (4)

• Figure 1: Posterior distributions of the GWB model parameters inferred from O3 data under Prior I. The red contours correspond to the CCSNe model, while the blue contours represent the combined CBC+CCSNe model. The parameters shown are: reference energy density $\log_{10} \Omega_{\mathrm{ref}}$, amplitude $\log_{10} A$, peak frequency $f_{\mathrm{peak}}$, and bandwidth $\Delta$.
• Figure 2: The 95% credibility upper limit on $\Omega_{\rm GW}(f)$ for the CBC+CCSNe model under two different priors. Also shown are predictions for the GWB from CBCs informed by GWTC-3 (including contributions from binary neutron stars, binary black holes and neutron star-black hole binaries), along with current and projected sensitivity curves LVK-O3-SGWB.
• Figure 3: Assuming a generic Gaussian emission spectrum, the required GW energy $E_{\mathrm{GW}}$ as a function of peak frequency $f_{\text{peak}}$ and spectral width $\Delta$ to achieve $(S/N)_{\mathrm{GWB}} = 3$ (top row) and a detection rate ($R_{\rm det}$) of 1 CCSNe event per year (bottom row). Panels correspond to different detectors A+ (left), CE (middle), and ET (right). Red dashed lines indicate constant levels of $E_{\mathrm{GW}}$.
• Figure 4: The signal to noise ratio of the GWB $(S/N)_{\rm GWB}$ (solid lines with shaded band) or the detection rate $R_{\rm det}$ (dashed lines with shaded band) of individual CCSNe events as a function the GW energy emitted by CCSNe events for the ET (left panel) or CE (right panel) detector. Blue and red curves denote two CCSNe spectral models (see text for details): Ott+11 s27-fheat1.05 (blue) and And+19 m15r (red). The crossing between the $(S/N)_{\rm GWB}$ lines and the $R_{\rm det}$ lines with their respective thresholds (horizontal lines) are marked with circles and squares (with the GW energy values listed), respectively. Two vertical lines are the upper limits derived in this work.