Abstract I present a scenario by which an accretion flow with alternating angular momentum on to a newly born neutron star in a core collapse supernova (CCSN) efficiently amplifies magnetic fields and by that launches jets. The accretion flow of a collapsing core on to the newly born neutron star suffers spiral standing accretion shock instability (SASI). This instability leads to a stochastically variable angular momentum of the accreted gas, which in turn forms an accretion flow with alternating directions of the angular momentum, and hence alternating shear, at any given time. I study the shear in this alternating-shear sub-Keplerian inflow in published simulations, and present a new comparison with Keplerian accretion disks. From that comparison I argue that it might be as efficient as Keplerian accretion disks in amplifying magnetic fields by a dynamo. I suggest that although the average specific angular momentum of the accretion flow is small, namely, sub-Keplerian, this alternating-shear accretion flow can launch jets with varying directions, namely, jittering jets. Neutrino heating is an important ingredient in further energizing the jets. The jittering jets locally revive the stalled accretion shock in the momentarily polar directions, and by that they explode the star. I repeat again my call for a paradigm shift from a neutrino-driven explosion of CCSNe to a jet-driven explosion mechanism that is aided by neutrino heating.
Keywords stars: jets — supernovae: general — stars: massive
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