<i>FUSE</i>Observations of Cooling‐Flow Gas in the Galaxy Clusters A1795 and A2597
Bibliographic record
Abstract
We present far-ultraviolet spectroscopy of the cores of the massive cooling-flow clusters Abell 1795 and 2597, obtained with the Far Ultraviolet Spectroscopic Explorer . As the intracluster gas cools through 3 × 10 5 K, it should emit strongly in the O VI λλ1032, 1038 resonance lines. We report the detection of O VI λ1032 emission in A2597, with a line flux of × 10 -15 ergs cm -2 s -1 , as well as detection of emission from C III λ977. A marginal detection of C III λ977 emission is also reported for A1795. These observations provide evidence for a direct link between the hot (10 7 K) cooling-flow gas and the cool (10 4 K) gas in the optical emission line filaments. Assuming simple cooling-flow models, the O VI line flux in A2597 corresponds to a mass deposition rate of ~40 M ☉ yr -1 within the central 36 kpc. Emission from O VI λ1032 was not detected in A1795, with an upper limit of 1.5 × 10 -15 ergs cm -2 s -1 , corresponding to a limit on the mass cooling-flow rate of (28 kpc) < 28 M ☉ yr -1 . We have considered several explanations for the lack of detection of O VI emission in A1795 and the weaker than expected flux in A2597, including extinction by dust in the outer cluster and quenching of thermal conduction by magnetic fields. We conclude that a turbulent mixing model, with some dust extinction, could explain our O VI results while also accounting for the puzzling lack of emission by Fe XVII in cluster cooling flows.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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".