Three-Dimensional General-Relativistic Simulations of Neutrino-Driven Winds from Rotating Proto-Neutron Stars

Abstract

We explore the effects of rapid rotation on the properties of neutrino-heated winds from proto-neutron stars (PNS) formed in core-collapse supernovae or neutron-star mergers by means of three-dimensional general-relativistic hydrodynamical simulations with M0 neutrino transport. We focus on conditions characteristic of a few seconds into the PNS cooling evolution when the neutrino luminosities obey $L_{\nu_e} + L_{\bar{\nu}_e} \approx 7\times 10^{51}$ erg s$^{-1}$, and over which most of the wind mass-loss will occur. After an initial transient phase, all of our models reach approximately steady-state outflow solutions with positive energies and sonic surfaces captured on the computational grid. Our non-rotating and slower-rotating models (angular velocity relative to Keplerian $\Omega/\Omega_{\rm K} \lesssim 0.4$; spin period $P \gtrsim 2$ ms) generate approximately spherically symmetric outflows with properties in good agreement with previous PNS wind studies. By contrast, our most rapidly spinning PNS solutions ($\Omega/\Omega_{\rm K} \gtrsim 0.75$; $P \approx 1$ ms) generate outflows focused in the rotational equatorial plane with much higher mass-loss rates (by over an order of magnitude), lower velocities, lower entropy, and lower asymptotic electron fractions, than otherwise similar non-rotating wind solutions. Although such rapidly spinning PNS are likely rare in nature, their atypical nucleosynthetic composition and outsized mass yields could render them important contributors of light neutron-rich nuclei compared to more common slowly rotating PNS birth. Our calculations pave the way to including the combined effects of rotation and a dynamically-important large-scale magnetic field on the wind properties within a 3D GRMHD framework.