SHOCK-ENHANCED C<sup>+</sup>EMISSION AND THE DETECTION OF H<sub>2</sub>O FROM THE STEPHAN'S QUINTET GROUP-WIDE SHOCK USING<i>HERSCHEL</i>
Bibliographic record
Abstract
We present the first Herschel spectroscopic detections of the [O i ] 63 μm and [C ii ] 158 μm fine-structure transitions, and a single para-H 2 O line from the 35 × 15 kpc 2 shocked intergalactic filament in Stephan's Quintet. The filament is believed to have been formed when a high-speed intruder to the group collided with a clumpy intergroup gas. Observations with the PACS spectrometer provide evidence for broad (>1000 km s −1 ) luminous [C ii ] line profiles, as well as fainter [O i ] 63 μm emission. SPIRE FTS observations reveal water emission from the p-H 2 O (1 11 –0 00 ) transition at several positions in the filament, but no other molecular lines. The H 2 O line is narrow and may be associated with denser intermediate-velocity gas experiencing the strongest shock-heating. The [C ii ]/PAH tot and [C ii ]/FIR ratios are too large to be explained by normal photo-electric heating in photodissociation regions. H ii region excitation or X-ray/cosmic-ray heating can also be ruled out. The observations lead to the conclusion that a large fraction the molecular gas is diffuse and warm. We propose that the [C ii ], [O i ], and warm H 2 line emission is powered by a turbulent cascade in which kinetic energy from the galaxy collision with the intergalactic medium is dissipated to small scales and low velocities, via shocks and turbulent eddies. Low-velocity magnetic shocks can help explain both the [C ii ]/[O i ] ratio, and the relatively high [C ii ]/H 2 ratios observed. The discovery that [C ii ] emission can be enhanced, in large-scale turbulent regions in collisional environments, has implications for the interpretation of [C ii ] emission in high- z galaxies.
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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) | 0.005 | 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".