The molecular gas properties in the gravitationally lensed merger HATLAS J142935.3–002836
Bibliographic record
Abstract
ABSTRACT Follow-up observations of (sub-)mm-selected gravitationally lensed systems have allowed a more detailed study of the dust-enshrouded phase of star formation up to very early cosmic times. Here, the case of the gravitationally lensed merger in HATLAS J142935.3–002836 (also known as H1429−0028; zlens = 0.218, zbkg = 1.027) is revisited following recent developments in the literature and new Atacama Pathfinder EXperiment (APEX) observations targeting two carbon monoxide (CO) rotational transitions Jup = 3 and 6. We show that the line profiles comprise three distinct velocity components, where the fainter high velocity one is less magnified and more compact. The modelling of the observed spectral line energy distribution of CO Jup = 2–6 and [C i] 3P1−3P0 assumes a large velocity gradient scenario, where the analysis is based on four statistical approaches. Since the detected gas and dust emission comes exclusively from only one of the two merging components (the one oriented north–south, NS), we are only able to determine upper limits for the companion. The molecular gas in the NS component in H1429−0028 is found to have a temperature of ∼70 K, a volume density of log (n[cm−3]) ∼ 3.7, to be expanding at ∼10 km s−1 pc−1, and amounts to ${M_{\rm H_2} = 4_{-2}^{+3} \times 10^9\,{\rm M}_\odot }$. The CO to H2 conversion factor is estimated to be $\alpha _{\rm CO} = 0.4_{-0.2}^{+0.3}\,$ M⊙/(K km s−1 pc2). The NS galaxy is expected to have a factor of ≳10× more gas than its companion (${M_{\rm H_2}}\lesssim 3\times 10^8$ M⊙). Nevertheless, the total amount of molecular gas in the system comprises only up to 15 per cent (1σ upper limit) of the total (dynamical) mass.
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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".