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 protoneutron stars (PNS) formed in core-collapse supernovae or neutron-star mergers by means of threedimensional 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 νe + L νe ≈ 7 × 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 slowerrotating models (angular velocity relative to Keplerian Ω/Ω K 0.4; spin period P 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 (Ω/Ω K 0.75; P ≈ 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.

Proto-Neutron Star Convection and the Neutrino-Driven Wind: Implications for the r-Process

“…The inclusion of corrections from general relativity tends to make conditions more favorable for the r-process, but a very high PNS mass is still required for a strong r-process to proceed (Cardall & Fuller 1997;Otsuki et al 2000;Thompson et al 2001). A number of studies have explored the effects of rotation and magnetic fields in varying dimensionality (Metzger et al 2007;Vlasov et al 2014;Thompson & ud Doula 2018;Desai et al 2022), further confirming that extreme conditions -high PNS masses and magnetar-strength magnetic fields -are required for conditions to favor an r-process.…”

Signatures of R-process Enrichment in Supernovae from Collapsars

“…More recent explorations have focused on rarer SN subtypes, such as explosions that leave behind very rapidly spinning (Desai et al 2022) and/or highly magnetized NSs (Thompson et al 2004;Metzger et al 2007) and their concomitant "jet-driven" SN explosions (Winteler et al 2012;Mösta et al 2014Mösta et al , 2018Kuroda et al 2020), in which the prompt advection of neutron-rich material away from the proto-NS surface avoids the problem of charged current interactions-neutrino capture and e + /e − pair creation and capture-that in the absence of rapid expansion thwart the r -process by protonizing the outflowing matter. However, 3D magnetohydrodynamic (MHD) simulations of the explosions ) cast doubt as to whether sufficiently rapid expansion can in fact be realized.…”