Investigating physical states of molecular gas in the overlapping region of interacting galaxies NGC 4567/4568 using ALMA
Bibliographic record
Abstract
Abstract We present ALMA observations of a diffuse gas tracer, CO(J = 1–0), and a warmer and denser gas tracer, CO(J = 3–2), in the overlapping region of interacting galaxies NGC 4567/4568, which are in the early stage of interaction. To understand the impact of galaxy interactions on molecular gas properties, we focus on interacting galaxies during the early stage and study their molecular gas properties. We investigate the physical states of a filamentary molecular structure at the overlapping region, which was previously reported. Utilizing new higher-resolution CO(J = 1–0) data, we identify molecular clouds within overlapping and disk regions. Although the molecular clouds in the filament have a factor of two higher average virial parameter (0.56 ± 0.14) than that in the overlapping region (0.28 ± 0.12) and in the disk region (0.26 ± 0.16), all the identified molecular clouds are gravitationally bound. These clouds in the filament also have a larger velocity dispersion than that in the overlapping region, suggesting that molecular gas and/or atomic gas with different velocities collide there. We calculate the ratio of the integrated intensity of CO(J = 3–2) and CO(J = 1–0) (= R3−2/1−0) on the molecular cloud scale. The maximum R3−2/1−0 is 0.17 ± 0.04 for all identified clouds. R3−2/1−0 for the molecular clouds in the filament is lower than that of the surrounding area. This result contradicts the predictions of previous numerical simulations, which suggested that the molecular gas on the collision front of galaxies is compressed and becomes denser. Our results imply that NGC 4567/4568 is in a very early stage of interaction; otherwise, the molecular clouds in the filament would not yet fulfill the conditions necessary to trigger star formation.
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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 | 0.001 |
| 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".