The Tully‐Fisher Relation in Cluster Cl 0024+1654 at<i>z</i> = 0.4
Bibliographic record
Abstract
Using moderate-resolution Keck spectra, we have examined the velocity profiles of 15 members of cluster Cl 0024+1654 at z = 0.4. WFPC2 images of the cluster members have been used to determine structural parameters, including disk sizes, orientations, and inclinations. We compare two methods of optical rotation curve analysis for kinematic measurements. Both methods take seeing, slit size and orientation, and instrumental effects into account and yield similar rotation velocity measurements. Four of the galaxies in our sample exhibit unusual kinematic signatures, such as noncircular motions. Our key result is that the Cl 0024 galaxies are marginally underluminous (0.50 ± 0.23 mag), given their rotation velocities, as compared to the local Tully-Fisher relation. In this analysis, we assume no slope evolution and take into account systematic differences between local and distant velocity and luminosity measurements. Our result is particularly striking considering that the Cl 0024 members have very strong emission lines and local galaxies with similar Hα equivalent widths tend to be overluminous on the Tully-Fisher relation. Cl 0024 Tully-Fisher residuals appear to be correlated most strongly with galaxy rotation velocities, indicating a possible change in the slope of the Tully-Fisher relation. However, we caution that this result may be strongly affected by magnitude selection and by the original slope assumed for the analysis. Cl 0024 residuals also depend weakly on color, emission-line strength and extent, and photometric asymmetry. In a comparison of stellar and gas motions in two Cl 0024 members, we find no evidence for counterrotating stars and gas, an expected signature of mergers.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".