A Model for the Accretion Disk of Hercules X-1 from 35-Day Cycle Lightcurves
Bibliographic record
Abstract
The binary Hercules X-1 exhibits a 35-day brightness X-ray cycle, including a Main High state and a Short High state which are separated by two Low states. The cycle is due to blockage of the neutron star by a rotating twisted disk. The best available 35-day average lightcurves are from Swift/BAT observations in the 15–50 keV band and from MAXI observations in the 2–20 keV band. The current work fits both Swift/BAT and MAXI 35-day X-ray lightcurves using a disk plus corona model. The parameters of the disk and its corona from the two data sets are shown to be consistent with each other. The fit of two different data sets with the same model verifies the reliabilty of the disk plus corona model and its parameter values. We derive the scaling of the model disk radius to physical disk radius and use that to find that the physical corona inner radius is very small ∼100 km, and consistent with the estimate from pulse shape analysis. The system inclination of 85.12±0.24° is consistent with the recent value derived from MAXI observations alone, and much improved compared to earlier estimates (∼82 to 88°). This results in significantly improved binary system parameters, including neutron star mass, companion mass and companion radius.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".