Minimal HCN emission from molecular clouds in M33
Bibliographic record
Abstract
Since HCN emission has been shown to be a linear tracer of ongoing star formation activity, we have searched for HCN (J= 1 → 0) emission from known GMCs in the nearby galaxy M33. No significant HCN emission has been found along any of the lines of sight. We find two lines of sight with CO-to-HCN integrated intensity ratios up to 280, nearly a factor of 6 above what is found in comparable regions of the Milky Way. Star formation tracers suggest that the HCN-to-star formation rate ratio () is a factor of 6 lower than what is observed in the Milky Way (on average) and local extragalactic systems. Simple chemical models accounting for the subsolar N/O ratio suggest that depletion cannot account for the high CO-to-HCN ratios. Given HCN formation requires high extinction (AV > 4), low metallicity may yield reduced dust shielding and thus a high CO/HCN ratio. The turbulence and structure of GMCs in M33 are comparable to those found in other systems, so the differences are unlikely to result from different GMC properties. Since lower CO-to-HCN ratios are associated with the highest rates of star formation, we attribute the deficits in part to evolutionary effects within GMCs.
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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".