Multi-Messenger Signatures of High-Energy Transients: Probing Extreme Physics from Collapse to Observation

High-energy astrophysical transients, such as the accretion-induced collapse of white dwarfs or interacting supernovae, serve as natural laboratories for extreme physics that cannot be reproduced in terrestrial experiments. In this talk, I will present a framework that connects the microphysics of stellar collapse and explosion to observable multi-messenger signatures across electromagnetic and neutrino channels. Using state-of-the-art GRMHD simulations combined with nuclear reaction networks and radiative transfer, I will show how observations—including kilonova–GRB associations and IceCube neutrino detections—can constrain the inner workings of these extreme environments, and discuss how upcoming surveys will help refine the physical parameters of these astrophysical systems.