Gas and Dust in NGC 7469: Submillimeter Imaging and CO<i>J</i> = 3–2
Bibliographic record
Abstract
We present sensitive submillimeter imaging of the Seyfert 1 galaxy NGC 7469 at 850 and 450 μm with the Submillimeter Common User Bolometer Array on the James Clerk Maxwell Telescope and 12 CO J = 3-2 line observations of its central starbursting region. The global dust spectrum, as constrained by the new set of submillimeter data and available 1.30 mm and IRAS 100 and 60 μm data, reveals a dominant warm dust component with a temperature of T d ~ 35 K and a global molecular gas-to-dust ratio M (H 2 )/ M d ~ 600. Including the atomic gas component yields a total gas-to-dust ratio of ~830. Such high values are typical for IR-bright spiral galaxies, and in order to reconcile them with the significantly lower ratio of ~100 obtained for the Milky Way, a cold dust reservoir, inconspicuous at far-infrared wavelengths, is usually postulated. However, while there is good evidence for the presence of cold gas/dust in NGC 7469 beyond its central region, our 450 μm map and available interferometric 12 CO J = 1-0 maps show the bright submillimeter/CO emission confined in the inner ~2.5 kpc, where a high 12 CO ( J = 3-2)/( J = 1-0) ratio (~0.85-1.0) is measured. This is consistent with molecular gas at T kin ≳ 30 K, suggesting that the bulk of the interstellar medium in the starburst center of NGC 7469 is warm. Nevertheless, the corresponding total gas-to-dust ratio there remains high, of the order of ~500. We argue that, rather than unaccounted cold dust mass, this high ratio suggests an overestimate of M (H 2 ) from its associated 12 CO J = 1-0 line luminosity by a factor of ~5 when a Milky Way value for this conversion is used. Finally, the diffuse cold gas and dust that is the likely source of the observed faint extended 450 μm and 12 CO J = 1-0 emission has an estimated total gas-to-dust ratio of ~50-160, closer to the Galactic value.
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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".