HCN(1–0) enhancement in the bar of NGC 2903
Bibliographic record
Abstract
We have mapped the HCN(1–0) emission from two spiral galaxies, NGC 2903 and NGC 3504 to study the gas properties in the bars. The HCN(1–0) emission is detected in the center and along the bar of NGC 2903. The line ratio HCN(1–0)/ 12CO(1–0) ranges from 0.07 to 0.12 with the lowest value in the center. The enhancement of HCN(1–0) emission along the bar indicates a higher fraction of dense molecular gas in the bar than at the center. The mass of dense molecular gas in the center (2.2 107 ) is about 6 times lower than that in the bar (1.2 108 ). The total star formation rate (SFR) is estimated to be 1.4 yr-1, where the SFR at the center is 1.9 times higher than that in the bar. The time scale of consumption of the dense molecular gas in the center is about ~ 3 107 yr which is much shorter than that in the bar of about 2 to 10 108 yr. The dynamical time scale of inflow of the gas from the bar to the center is shorter than the consumption time scale in the bar, which suggests that the star formation (SF) activity at the center is not deprived of fuel. In the bar, the fraction of dense molecular gas mass relative to the total molecular gas mass is twice as high along the leading edge than along the central axis of the bar. The HCN(1–0) emission has a large velocity dispersion in the bar, which can be attributed partially to the streaming motions indicative of shocks along the bar. In NGC 3504, the HCN(1–0) emission is detected only at the center. The fraction of dense molecular gas mass in the center is about 15%. Comparison of the SFR with the predictions from numerical simulations suggest that NGC 2903 harbors a young type B bar with a strong inflow of gas toward the center whereas NGC 3504 has an older bar and has already passed the phase of inflow of gas toward the center.
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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 | 0.000 |
| 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".