Neutrino-heated winds from rotating proto-magnetars

TL;DR

This paper models neutrino-driven winds from rotating, magnetized proto-neutron stars to evaluate their potential as sites for r-process nucleosynthesis and gamma-ray burst engines, highlighting the influence of rotation and magnetic fields.

Contribution

It provides a detailed calculation of steady-state wind properties from proto-magnetars considering magnetic and rotational effects, advancing understanding of their role in nucleosynthesis and GRB production.

Findings

Proto-magnetars with 2-5 ms periods favor third-peak r-process nucleosynthesis.

Moderately rapid proto-magnetars (3-5 ms) could be significant Galactic r-process sites.

Fast rotators (1-2 ms) can produce ultra-relativistic jets suitable for gamma-ray bursts.

Abstract

We calculate the steady-state properties of neutrino-driven winds from strongly magnetized, rotating proto-neutron stars (`proto-magnetars') under the assumption that the outflow geometry is set by the force-free magnetic field of an aligned dipole. Our goal is to assess proto-magnetars as sites of r-process nucleosynthesis and gamma-ray burst engines. One dimensional solutions calculated along flux tubes corresponding to different polar field lines are stitched together to determine the global properties of the flow at a given neutrino luminosity and rotation period. Proto-magnetars with rotation periods of P~2-5 ms are shown to produce outflows more favorable for the production of third-peak r-process nuclei due to their much shorter expansion times through the seed nucleus formation region, yet only moderately lower entropies, as compared to normal spherical PNS winds. Proto-magnetars with moderately rapid birth periods P~3-5 ms may thus represent a promising Galactic r-process site which is compatible with a variety of other observations, including the recent discovery of possible magnetar-powered supernovae in metal poor galaxies. We also confirm previous results that the outflows from proto-magnetars with P~1-2 ms can achieve maximum Lorentz factors Gamma ~ 100-1000 in the range necessary to power gamma-ray bursts (GRBs). The implications of GRB jets with a heavy nuclei-dominated composition as sources of ultra-high energy cosmic rays are also addressed.