Evolution of the disc atmosphere in the X-ray binary MXB 1659-298, during its 2015-2017 outburst
Bibliographic record
Abstract
We report on the evolution of the X-ray emission of the accreting neutron star (NS) low-mass X-ray binary (LMXB), MXB 1659-298, during its most recent outburst in 2015–17. We detected 60 absorption lines during the soft state (of which 21 at more than 3σ), that disappeared in the hard state (e.g. the Fe xxv and Fe xxvi lines). The absorbing plasma is at rest, likely part of the accretion disc atmosphere. The bulk of the absorption features can be reproduced by a high column density (log (NH/cm−2) ∼ 23.5) of highly ionized (log (ξ/erg cm s−1) ∼ 3.8) plasma. Its disappearance during the hard state is likely the consequence of a thermal photo-ionization instability. MXB 1659-298’s continuum emission can be described by the sum of an absorbed disc blackbody and its Comptonised emission, plus a blackbody component. The observed spectral evolution with state is in line with that typically observed in atoll and stellar mass black hole LMXB. The presence of a relativistic Fe K α disc-line is required during the soft state. We also tentatively detect the Fe xxii doublet, whose ratio suggests an electron density of the absorber of ne > 1013 cm−3, hence, the absorber is likely located at <7 × 104 rg from the illuminating source, well inside the Compton and outer disc radii. MXB 1659-298 is the third well monitored atoll LMXB showcasing intense Fe xxv and Fe xxvi absorption during the soft state that disappears during the hard state.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".