r-Process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments

Abstract

We investigate $r$-process nucleosynthesis in three-dimensional general\nrelativistic magnetohydrodynamic simulations of jet-driven supernovae resulting\nfrom rapidly rotating, strongly magnetized core-collapse. We explore the effect\nof misaligning the pre-collapse magnetic field with respect to the rotation\naxis by performing four simulations: one aligned model and models with 15, 30,\nand 45 degree misalignments. The simulations we present employ a microphysical\nfinite-temperature equation of state and a leakage scheme that captures the\noverall energetics and lepton number exchange due to post-bounce neutrino\nemission and absorption. We track the thermodynamic properties of the ejected\nmaterial with Lagrangian tracer particles and analyse its composition with the\nnuclear reaction network SkyNet. By using different neutrino luminosities in\npost-processing the tracer data with SkyNet, we constrain the impact of\nuncertainties in neutrino luminosities. We find that, for the aligned model\nconsidered here, the use of an approximate leakage scheme results in neutrino\nluminosity uncertainties corresponding to a factor of 100-1000 uncertainty in\nthe abundance of third peak $r$-process elements. Our results show that for\nmisalignments of 30 degrees or less, $r$-process elements are robustly produced\nas long as neutrino luminosities are reasonably low ($\\lesssim 5 \\times\n10^{52}$ erg s$^{-1}$). For a more extreme misalignment of 45 degrees, we find\nthe production of $r$-process elements beyond the second peak significantly\nreduced. We conclude that robust $r$-process nucleosynthesis in\nmagnetorotational supernovae requires a progenitor stellar core with a large\npoloidal magnetic field component that is at least moderately (within $\\sim 30$\ndegrees) aligned with the rotation axis.\n