N2H+(1–0) as a tracer of dense gas in and between spiral arms
Bibliographic record
Abstract
ABSTRACT Recent advances in identifying giant molecular filaments in Galactic surveys allow us to study the interstellar material and its dense, potentially star forming phase on scales comparable to resolved extragalactic clouds. Two large filaments detected in the 13CO/C18O(J = 3–2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) survey, one in the Sagittarius-arm and one in an interarm region, were mapped with dense gas tracers inside a 0.06 square degrees area and with a spatial resolution of around 0.4 and 0.65 pc at the distance of the targets using the 30 m telescope of the Institut de Radioastronomie Millimétrique (IRAM) to investigate the environmental dependence of the dense gas fraction. The N2H+(1 − 0) transition, an excellent tracer of the dense gas, was detected in parsec-scale, elliptical clumps and with a filling factor of around 8.5 per cent in our maps. The N2H+-emitting areas appear to have higher dense gas fraction (e.g. the ratio of N2H+ and 13CO emission) in the interarm than in the arm which is opposite to the behaviour found by previous studies, using dust emission rather than N2H+ as a tracer of dense gas. However, the arm filament is brighter in 13CO and the infrared emission of dust, and the dense gas fraction determined as above is governed by the 13CO brightness. We caution that measurements regarding the distribution and fraction of dense gas on these scales may be influenced by many scale- and environment-dependent factors, as well as the chemistry and excitation of the particular tracers, then consider several scenarios that can reproduce the observed effect.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".