Evolution and Environment of Early-Type Galaxies
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
We study the photometric and spectral properties of 39320 early-type galaxies within the SDSS, as a function of both local environment and redshift. The distance to the nearest cluster of galaxies and the distance to the 10th nearest luminous neighbor were used to define two extremes in environment. The properties of early-type galaxies are weakly but significantly different in these two extremes: objects in dense environments are less than ~1 Gyr older and alpha-enhanced by ~0.02 relative to their counterparts of the same velocity dispersion in less dense regions, but the metallicities show no dependence on environment. This suggests that, in dense regions, the stars in early-type galaxies formed at slightly earlier times, and on a slightly shorter timescale, than in less dense regions. In addition, objects at lower redshifts are older, but have the same metallicities and alpha-enhancements as their counterparts of the same sigma at higher redshifts, as expected if the low redshift sample is a passively-aged version of the sample at higher redshifts. These significant conclusions are derived from several pieces of evidence discussed in this paper, including the FP of early-types, the observed evolution of absorption linestrengths (measured from a large ensemble of composite spectra which we provide in tabular form) over small lookback times, and comparison with the predictions of single burst (non-solar abundance) stellar population synthesis models (which also indicate that age, metallicity and alpha-enhancement all increase with velocity dispersion).
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.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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 it