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A Model for the Accretion Disk of Hercules X-1 from 35-Day Cycle Lightcurves

2025· preprint· W4415680639 on OpenAlexfundno aff
D. A. Leahy

Bibliographic record

VenuePreprints.org · 2025
Typepreprint
Language
FieldPhysics and Astronomy
TopicAstrophysical Phenomena and Observations
Canadian institutionsnot available
FundersNatural Sciences and Engineering Research Council of Canada
KeywordsCorona (planetary geology)Neutron starAccretion discRADIUSAccretion (finance)Binary numberIntermediate polar

Abstract

fetched live from OpenAlex

The 35-day X-ray lightcurve of Hercules X-1 consists of a Main High state, a Short High state and two Low states. These are caused by a precessing tilted and twisted accretion 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 the 35-day X-ray lightcurve from Swift/BAT and fits the MAXI 35-day X-ray lightcurve using a disk plus corona model. The parameters of the disk and its corona from the two data sets are consistent with eachother. 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 find the inner corona radius is significantly smaller than the inner disk radius, consistent with the conclusions of pulse shape studies. The system inclination of $85.12\pm0.24^{\circ}$ is consistent with the recent value derived from MAXI observations alone, and much improved compared to earlier estimates ($\sim$82 to 88$^\circ$). This results is significantly improved binary system parameters, including neutron star mass, companion mass and companion radius.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Simulation or modeling · Consensus signal: Simulation or modeling
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.018
Threshold uncertainty score0.036

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0010.000
Meta-epidemiology (broad)0.0000.001
Bibliometrics0.0010.001
Science and technology studies0.0000.000
Scholarly communication0.0010.001
Open science0.0010.000
Research integrity0.0010.000
Insufficient payload (model declined to judge)0.0030.001

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.

Opus teacher head0.108
GPT teacher head0.331
Teacher spread0.223 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designSimulation or modeling
Domainnot available
GenreEmpirical

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".

Quick stats

Citations0
Published2025
Admission routes1
Has abstractyes

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