VERTICO – IX. Signatures of environmental processing of the gas in Virgo cluster spiral galaxies through mapping of CO isotopologues
Bibliographic record
Abstract
ABSTRACT In this work, we study CO isotopologue emission in the largest cluster galaxy sample to date: 48 VERTICO spiral galaxies in Virgo. We show for the first time in a significant sample that the physical conditions within the molecular gas appear to change as a galaxy’s interstellar medium (ISM) is affected by environmental processes. $^{13}$CO is detected across the sample, both directly and via stacking, while C$^{18}$O is detected in a smaller number of systems. We use these data to study trends with global and radial galaxy properties. We show that the $^{12}$CO/$^{13}$CO line ratio changes systematically with a variety of galaxy properties, including mean gas surface density, H i-deficiency, and galaxy morphology. $^{13}$CO/C$^{18}$O line ratios vary significantly, both radially and between galaxies, suggesting real variations in abundances are present. Such abundance changes may be due to star formation history differences, or speculatively even stellar initial mass function variations. We present a model where the optical depth of the molecular gas appears to change as a galaxy’s ISM is affected by environmental processes. The molecular gas appears to become more transparent as the molecular medium is stripped, and then more opaque as the tightly bound remnant gas settles deep in the galaxy core. This explains the variations we see, and also helps explain similar observations in cluster early-type galaxies. Next generation simulations and dedicated observations of additional isotopologues could thus provide a powerful tool to help us understand the impact of environment on the ISM, and thus the quenching of galaxies.
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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 | 0.001 | 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".