Asymmetric core collapse of rapidly rotating massive star

TL;DR

This study uses 3D hydrodynamic simulations to explore how rapid rotation in massive stars influences core collapse, magnetic field amplification, bipolar outflows, and nucleosynthesis, with implications for supernovae and neutron star kicks.

Contribution

It provides new insights into the asymmetric core collapse of rapidly rotating massive stars and the resulting phenomena like magnetic amplification and bipolar outflows.

Findings

Formation of a rotating proto-neutron star with a natal kick.

Magnetic field amplification in turbulent, high-shear regions.

Potential for r-process nucleosynthesis near the proto-neutron star.

Abstract

Non-axisymmetric features are found in the core collapse of a rapidly rotating massive star, which might have important implications for magnetic field amplification and production of a bipolar outflow that can explode the star, as well as for r-process nucleosynthesis and natal kicks. The collapse of an evolved rapidly rotating massive star is followed in three-dimensional hydrodynamic simulations using the FLASH code with neutrino leakage. A rotating proto-neutron star (PNS) forms with a non-zero linear velocity. This can contribute to the natal kick of the remnant compact object. The PNS is surrounded by a turbulent medium, where high shearing is likely to amplify magnetic fields, which in turn can drive a bipolar outflow. Neutron-rich material in the PNS vicinity might induce strong r-process nucleosynthesis. The rapidly rotating PNS possesses a rotational energy of E>10foe. Magnetar formation proceeding in a similar fashion will be able to deposit a portion of this energy later on in the supernova ejecta through a spin down mechanism. These processes can be important for rare supernovae generated by rapidly rotating progenitors, even though a complete explosion is not simulated in the present study.