Full Transport General Relativistic Radiation Magnetohydrodynamics for Nucleosynthesis in Collapsars

TL;DR

This study employs full general relativistic radiation magnetohydrodynamics to model collapsar systems, revealing that accurate neutrino transport influences outflows and inhibits the formation of third peak r-process elements, impacting nucleosynthesis predictions.

Contribution

It introduces a comprehensive model with frequency-dependent neutrino transport for collapsars, highlighting the importance of detailed physics in predicting nucleosynthesis outcomes.

Findings

Accurate transport raises electron fraction in outflows.

Prevents synthesis of third peak r-process material.

Emphasizes need for realistic initial conditions.

Abstract

We model a compact black hole-accretion disk system in the collapsar scenario with full transport, frequency dependent, general relativistic radiation magnetohydrodynamics. We examine whether or not winds from a collapsar disk can undergo rapid neutron capture (r-process) nucleosynthesis and significantly contribute to solar r-process abundances. We find the inclusion of accurate transport has significant effects on outflows, raising the electron fraction above $Y_{\rm e} \sim 0.3$ and preventing third peak r-process material from being synthesized. We analyze the time-evolution of neutrino processes and electron fraction in the disk and present a simple one-dimensional model for the vertical structure that emerges. We compare our simulation to semi-analytic expectations and argue that accurate neutrino transport and realistic initial and boundary conditions are required to capture the dynamics and nucleosynthetic outcome of a collapsar.