Nobeyama Millimeter Array CO (<i>J</i> = 1–0) Observations of the Hα/Radio Lobe Galaxy NGC 3079: Gas Dynamics in a Weak Bar Potential and Central Massive Core
Bibliographic record
Abstract
We present 12 CO (1-0) observations in the central 4.5 kpc (1') of the Hα/radio lobe galaxy NGC 3079 with the Nobeyama Millimeter Array. The molecular gas shows four components: a main disk, spiral arms, a nuclear disk, and a nuclear core. The main disk extends along the galaxy major axis. We detected its central 2 kpc radius, while its full extent is beyond our spatial coverage. Molecular gas is smoothly distributed in the main disk, having a gas mass of 5 × 10 9 M ☉ within the central ~2 kpc radius. The spiral arms are superimposed on the main disk. Abrupt velocity changes of up to ~200 km s -1 are observed along the spiral arms in S-shaped twists of isovelocity contours and double velocity-peaked features on the spectra. The nuclear disk with ~600 pc radius appears in position-velocity (PV) diagrams, having an intense concentration of molecular gas. Its appearance on PV diagrams is indicative of oval motions of the gas, rather than circular. The nuclear disk and spiral arms form the so-called figure-of-eight pattern on a PV diagram. The nuclear core is more compact than our current resolution (2'' = 150 pc) and has a gas mass of 3 × 10 8 M ☉ within the central 150 pc. Although it is unresolved, the nuclear core shows a very high velocity ~200 km s -1 even at the radius of ~100 pc on the PV diagram. We propose a model that NGC 3079 contains a weak bar. The weak bar model explains the observed features of the main disk, spiral arms, and nuclear disk. The main disk and spiral arms result from gaseous x 1 -orbits and associated crowding, respectively. The nuclear disk arises from gaseous x 2 -orbits. The gas concentration in the nuclear disk could be explained by the expected gas-fueling mechanism: the gas on x 1 -orbits flows along spiral arms (or offset shocks), colliding with the gas on x 2 -orbits, and accumulating onto the nuclear disk. Assuming that the gas moves nearly along the spiral arms that run perpendicular to the line of sight, the pattern speed of the bar is estimated to be 55 ± 10 km s -1 kpc -1 . The high velocity of the nuclear core cannot be explained by our model for a bar. Thus we attribute it to a central massive core with a dynamical mass of 10 9 M ☉ within the central 100 pc. This mass is 3 orders of magnitude more massive than that of a central black hole in this galaxy.
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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) | 0.002 | 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".