Probing stellar populations and interstellar medium in early-type central galaxies
Bibliographic record
Abstract
ABSTRACT In this study, we analyse the characteristics of stellar populations and the interstellar medium (ISM) in 15 107 early-type central galaxies from the SPIDER survey. Using optical spectra from the Sloan Digital Sky Survey (SDSS), we investigate stellar age (Age), metallicity (Z), visual extinction (AV), and H α equivalent width (EWH α) to understand the evolution of the baryonic content in these galaxies. Our analysis explores the relationship between these properties and central velocity dispersion (σ) and halo mass (Mhalo) for isolated centrals (ICs) and group centrals (GCs). Our results confirm that both ICs and GCs’ stellar populations and gas properties are mainly influenced by σ, with Mhalo playing a secondary role. Higher σ values correspond to older, more metal-rich stellar populations in both ICs and GCs. Moreover, fixed σ values we observe younger Ages at higher values of Mhalo, a consistent trend in both ICs and GCs. Furthermore, we investigate the ionization source of the warm gas and propose a scenario where the properties of ionized gas are shaped by a combination of cooling within the intracluster medium (ICM) and feedback from Active Galactic Nuclei (AGNs) assuming a Bondi accretion regime. We observe inherent differences between ICs and GCs, suggesting that the ratio between AGN kinetic power and ICM thermal energy influences EWH α in ICs. Meanwhile, gas deposition in GCs appears to involve a more complex interplay beyond a singular AGN–ICM interaction.
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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".