Extracting SASI signatures from gravitational waves of core-collapse supernovae using the Hilbert-Huang transform

Core-collapse supernovae are among the most energetic astrophysical events in the Universe. Despite huge efforts in understanding the main ingredients triggering such explosions, we still lack compelling evidence for the precise mechanism driving these phenomena. They are expected to produce gravitational waves due to asymmetric mass motions in the collapsing core, and meanwhile emit neutrinos as a result of the interactions in their high-density environment. The combination of these two cosmic messengers can provide a unique probe to study the inner engine of these processes and unveil the explosion mechanism. Among the possible detectable signature, standing accretion shock instabilities (SASIs) are particularly relevant in this context, as they establish a direct connection between gravitational wave emission and the outgoing neutrino flux. In this work, Hilbert-Huang transform is applied to a selected sample of 3D numerical simulations, with the aim of identifying the SASI contribution and extracting its instantaneous frequency. The performance of the method is evaluated in the context of Einstein Telescope.