Gravitational waves from core-collapse supernovae with no electromagnetic counterparts

Abstract Core-collapse supernovae (CCSNe) are regularly observed electromagnetically, prompting targeted searches for their gravitational-wave emission. However, there are scenarios where these powerful explosions may not have any observable electromagnetic signal, but would still have strong detectable emission in gravitational waves and neutrinos. A regular CCSN explosion may be obscured by matter in the Galaxy. A star may undergo a failed CCSN explosion, where the stalled shockwave is not revived, and would eventually form a black hole. Higher mass progenitor stars may revive the shock, but form a black hole too quickly for the shockwave to reach the surface of the star and produce an electromagnetic signal. Previous work has shown that we can determine if a black hole forms from the CCSN neutrino emission if there are long-duration sinusoidal modulations in the neutrino signal caused by the standing accretion shock instability (SASI). The SASI also produces an observable signature in the gravitational-wave emission. In this paper, we investigate if we can distinguish between different scenarios for electromagnetically dark CCSNe using the gravitational-wave emission alone. We find, using a reconstruction of the SASI mode, abrupt end times of the gravitational-wave emission, and the rate of change of frequency of the dominant mode, that we are able to accurately distinguish between an obscured CCSN, a failed CCSN, and an explosion with fast black hole formation.