Collapsar disk outflows: Viscous hydrodynamic evolution in axisymmetry
Bibliographic record
Abstract
We investigate mass ejection from accretion disks formed during the collapse of rapidly rotating Wolf-Rayet stars. The neutrino-cooled, black hole (BH) accretion disk system that forms at the center of the star---and the ensuing outflows---provides the conditions for these systems to be candidate $r$-process element production sites and potential progenitors of broad-line type Ic (Ic-BL) supernovae. We present global, long-term axisymmetric hydrodynamic simulations of collapsar disks that include angular momentum transport through shear viscosity, neutrino emission and absorption, a 19-isotope nuclear reaction network and nuclear statistical equilibrium solver, a pseudo-Newtonian BH with mass and spin modified by accreted matter, and self-gravity. Starting with a stellar profile collapsed in spherical symmetry, our models capture disk formation self-consistently and are evolved until after the shock wave---driven by disk winds---reaches the surface of the star. None of our models achieve sufficient neutronization to eject significant amounts of $r$-process elements (detailed nucleosynthesis calculations will follow in a companion paper). Sufficient $^{56}\mathrm{Ni}$ is produced to power a typical type Ic-BL supernova light curve, but the average asymptotic velocity is a factor $\ensuremath{\sim}2$ to 3 times too slow to account for the typical linewidths in type Ic-BL supernova spectra. The gap in neutrino emission between BH formation and shocked disk formation and the magnitude of the subsequent peak in emission would be observable diagnostics of the internal conditions of the progenitor in a galactic collapsar. Periodic oscillations of the shocked disk prior to its expansion are also a potential observable through their impact on the neutrino and gravitational wave signals.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".