Evidence for Rapid Redshift Evolution of Strong Cluster Cooling Flows
Bibliographic record
Abstract
We present equivalent widths of the [OII]λ3727 and Hα nebular emission lines for 77 brightest cluster galaxies (BCGs) selected from the 160 Square Degree ROSAT X-ray survey. We find no [OII]λ3727 or Hα emission stronger than −15 A ̊ or −5 Å, respectively, in any BCG. The corresponding emission line luminosities lie below L ∼ 6×1040 erg s−1, which is a factor of 30 below that of NGC1275 in the Perseus cluster. A comparison to the detection frequency of nebular emission in BCGs at z ∼< 0.35 drawn from the Brightest Cluster Survey (Crawford et al. 1999) indicates that we should have detected roughly one dozen emission-line galaxies, assuming the two surveys are selecting similar clusters in the X-ray luminosity range 1042 erg s−1 to 1045 erg s−1. The absence of luminous nebular emission (ie., Perseus-like systems) in our sample is consistent with an increase in the number density of strong cooling flow (cooling core) clusters between z = 0.5 and today. The decline in their numbers at higher redshift could be due to cluster mergers and AGN heating.
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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 | 0.001 |
| 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".