Ultraviolet Observations of the X‐Ray Photoionized Wind of Cygnus X‐1 during X‐Ray Soft/High State1
Bibliographic record
Abstract
High-resolution ultraviolet observations of Cygnus X-1 were obtained at two epochs roughly 1 year apart using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope . Orbital phase ranges around ϕ orb = 0 and 0.5 were covered at each epoch, and the spectra show P Cygni line features from high (N V, C IV, Si IV) and absorption lines from low (Si II, C II) ionization state material. The high-ionization P Cygni profiles show a marked dependence on orbital phase; strong, broad absorption components when the X-ray source is behind the companion star and noticeably weaker absorption when the X-ray source is between us and the companion star. We fit the P Cygni profiles using the Sobolev with exact integration method applied to a spherically symmetric stellar wind subject to X-ray photoionization from the black hole. Of the wind-formed lines, the Si IV doublet provides the most reliable estimates of the parameters of the wind and X-ray illumination. The velocity v increases with radius r (normalized to the stellar radius) according to v = v ∞ (1 − r ⋆ / r ) β , with β ≈ 0.75 and v ∞ ≈ 1420 km s −1 . Our fit implies a ratio of X-ray luminosity (in units of 10 38 erg s −1 ) to wind mass-loss rate (in units of 10 −6 M ☉ yr −1 ) of L X,38 / −6 ≈ 0.033, measured at −6 = 4.8. Our models determine parameters that may be used to estimate the accretion rate onto the black hole and independently predict the X-ray luminosity. Our predicted L X matches that determined by contemporaneous RXTE ASM remarkably well, but is a factor of 3 lower than the rate according to Bondi-Hoyle-Littleton spherical wind accretion. We suggest that some of the energy of accretion may go into powering a jet.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".