SMA<sup>12</sup>CO(<i>J</i>= 6 – 5) AND 435 μm INTERFEROMETRIC IMAGING OF THE NUCLEAR REGION OF Arp 220
Bibliographic record
Abstract
We have used the Submillimeter Array (SMA) to make the first interferometric observations (beam size ∼1'' or ∼400 pc) of the 12 CO J = 6 − 5 line and 435 μm (690 GHz) continuum emission toward the central region (half power field of view 17'') of the nearby ultra-luminous infrared galaxy (ULIRG) Arp 220. These observations resolve the eastern and western nuclei from each other, in both the molecular line and dust continuum emission. At 435 μm, the peak intensity of the western nucleus is stronger than the eastern nucleus, and the difference in peak intensities is less than at longer wavelengths. Fitting a simple model to the dust emission observed between 1.3 mm and 435 μm suggests that dust emissivity power law index in the western nucleus is near unity and steeper in the eastern nucleus, about 2, and that the dust emission is optically thick at the shorter wavelength. Comparison with single dish measurements indicate that the interferometer observations are missing ∼60% of the dust emission, most likely from a spatially extended component to which these observations are not sensitive. The 12 CO J = 6 − 5 line observations clearly resolve kinematically the two nuclei. The distribution and kinematics of the 12 CO J = 6 − 5 line appear to be very similar to lower J CO lies observed at similar resolution. Analysis of multiple 12 CO line intensities indicates that the molecular gas in both nuclei have similar excitation conditions, although the western nucleus is warmer and denser. The excitation conditions are similar to those found in other extreme environments, including the nearby starburst galaxy M82, the active galactic nucleus (AGN) hosting ULIRG Mrk 231, and the high- z QSO BR 1202–0725. Simultaneous lower resolution observations of the 12 CO, 13 CO, and C 18 O J = 2 − 1 lines show that the 13 CO and C 18 O lines have similar intensities, which suggests that both of these lines are optically thick, or possibly that extreme high mass star formation has produced in an overabundance of C 18 O.
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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".