Structure and Nuclear Composition of General Relativistic, Magnetohydrodynamic Outflows from Neutrino-Cooled Disks

TL;DR

This paper models the structure and neutronization of GRMHD outflows from neutrino-cooled disks, revealing how different driving mechanisms affect their composition and relativistic nature.

Contribution

It provides a detailed analysis of outflow composition and structure considering various driving mechanisms in a relativistic MHD framework.

Findings

Thermally driven outflows become proton rich and can be magnetically dominated.

Centrifugally driven and turbulence-driven outflows can retain neutron excess.

Most outflows are subrelativistic due to large mass flux.

Abstract

We compute the structure and degree of neutronization of general relativistic magnetohydrodynamic (GRMHD) outflows originating from the inner region of neutrino-cooled disks. We consider both, outflows expelled from a hydrostatic disk corona and outflows driven by disk turbulence. We show that in outflows driven thermally from a static disk the electron fraction quickly evolves to its equilibrium value which is dominated by neutrino capture. Those outflows are generally proton rich and, under certain conditions, can be magnetically dominated. They may also provide sites for effective production of 56Ni. Centrifugally driven outflows and outflows driven by disk turbulence, on the other hand, can preserve the large in-disk neutron excess. Those outflows are, quite generally, subrelativistic by virtue of the large mass flux driven by the additional forces.