End-to-end modelling of magnetorotational core-collapse supernovae

Gamma Ray Bursts (GRBs) and broad-lined type-Ic supernovae (SNe Ic-bl) are some of the most powerful explosions in the universe. GRBs are short and intense flashes of gamma rays at cosmological distances. SNe Ic-bl, also known as hypernovae, are a subset of Type Ic supernovae which show unusually high kinetic energies (10 times that of typical SNe) that cannot be explained by the energy supplied by neutrinos alone. These systems represent some of the most extreme events in the universe and have the potential to uncover new physics in the multi-messenger era, but the mechanisms driving them are still unclear. SNe Ic-bl and long GRBs have been confirmed to be connected observationally, and a jet-driven explosion mechanism can explain both. However, it is not clear whether a proto-magnetar or a black hole produces the jet (also known as "central engine"). In this thesis, I investigate the feasibility of the magnetar model as the central engine. I have developed an end-to-end modelling pipeline which connects central engine simulations (that only cover the inner part of the star) to the light-curves and spectra of these events (which we observe on Earth). As the cornerstone project of this thesis I have developed a new GRMHD code GRaM-X which can perform simulations of core-collase supernovae on GPU supercomputers in full GR. To demonstrate the production-level capablities of GRaM-X I perform a long term three-dimensional jet-driven core-collapse supernova simulation of a 25 solar-mass progenitor and find that shock speeds reach canonical SN Ic-bl value of 20000 km/s.