Do collapsar accretion disks eject neutron-rich r-process matter?
In plain words
The disk around a black hole born inside a collapsing star could blow off neutron-rich gas that makes gold, but whether the gas stays neutron-rich enough is disputed.
Precise statement
In GRMHD simulations of collapsar disks (accretion rates $1e-3\text{ to }1\,M_{\mathrm{sun}}/\mathrm{s}$) with neutrino transport, determine the electron-fraction $Y_{e}$ distribution of the outflows and the mass with $Y_{e} < 0.25$ needed for lanthanides and the third r-process peak. Answer: r-process yield per event in $M_{\mathrm{sun}}$, with the dependence on neutrino-transport method quantified.
What would settle it
Converged simulations with Monte Carlo or moment neutrino transport from independent groups, plus detection or exclusion of r-process emission in late spectra of GRB supernovae.
Status in the literature
Simulations since 2020 with more detailed neutrino transport found less neutron-rich outflows than the 2019 estimate that collapsars could dominate.
Related problems
- Special case of Which site dominates the r-process inventory of the Milky Way?