Hall effect in neutron star crusts: evolution, endpoint and dependence on initial conditions
Bibliographic record
Abstract
We present new simulations of the evolution of axially symmetric magnetic fields in neutron star crusts under the influence of the Hall effect and subdominant Ohmic dissipation. In the Hall effect, differential rotation of the electron fluid generates toroidal field by winding of the poloidal field. For this reason, we focus on the influence of the initial choice of the electron angular velocity profile on the subsequent and long-term magnetic evolution. Whereas previous simulations have generally chosen angular velocities increasing outwards, corresponding to the lowest order Ohmic mode in the crust; a more realistic choice is an angular velocity decreasing outwards, corresponding to the magnetohydrodynamic equilibrium field that is likely present at the time of crust formation. We find that the evolution passes through three basic phases. The early evolution is a response to the initial conditions. During the second phase, the field consists of poloidal and toroidal components which eventually relax to an isorotation state in which the angular velocity of the electrons becomes constant along poloidal magnetic field lines, causing Hall evolution to saturate. In the third phase, the field dissipates slowly while maintaining isorotation. We discuss the implications for the long-term field structure and observable properties of isolated neutron stars.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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) | 0.002 | 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".