An Equilibrium Model of the Galaxy Determined by Element Abundance Gradients
Bibliographic record
Abstract
Abstract We present a method to determine the gravitational potential of the Milky Way from measurements of the locations, velocities, and element abundances of stars in the Galactic disk. The method relies on the assumption that the Galaxy is axisymmetric and stationary and that element abundance ratios such as [Fe/H] and [Mg/Fe] are smooth functions of three isolating integrals of motion. We use Fisher Information theory to predict the efficacy of individual abundance ratios to constrain the potential. We also use N-body simulations to test the extent by which secular evolution in the disk introduces statistical and systematic errors into the analysis. We apply our method to a sample of stars from Gaia Data Release 3 and the APOGEE survey and infer the vertical force profile at the position of the Sun and the rotation curve in the midplane and find good agreement with previously published results. The residuals of the model show corrugations in [Fe/H] as a function of L z , the angular momentum component along the spin axis of the Galaxy. Using the correspondence between L z and Galactocentric cylindrical radius, we show that these features line up with the four spiral arms closest to the Sun.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".