The complete local volume groups sample – III. Characteristics of group central radio galaxies in the Local Universe
Bibliographic record
Abstract
ABSTRACT Using new 610 and 235 MHz observations from the giant metrewave radio telescope (GMRT) in combination with archival GMRT and very large array (VLA) survey data, we present the radio properties of the dominant early-type galaxies in the low-richness subsample of the complete local-volume groups sample (CLoGS; 27 galaxy groups) and provide results for the radio properties of the full CLoGS sample for the first time. We find a high radio detection rate in the dominant galaxies of the low-richness subsample of 82 per cent (22/27); for the full CLoGS sample the detection rate is 87 per cent (46/53). The group-dominant galaxies exhibit a wide range of radio power, 1020–1025 W Hz−1 in the 235 and 610 MHz bands, with the majority (53 per cent) presenting point-like radio emission, 19 per cent hosting currently active radio jets, 6 per cent having remnant jets, 9 per cent being diffuse, and 13 per cent having no detected radio emission. The mean spectral index of the detected radio sources in the 235−610 MHz frequency range is found to be $\alpha _{235}^{610}\sim$0.68, and $\alpha _{235}^{1400}\sim$0.59 in the 235−1400 MHz one. In agreement with earlier studies, we find that the fraction of ultrasteep spectrum sources (α > 1.3) is ∼4 per cent, mostly dependent on the detection limit at 235 MHz. The majority of point-like systems are found to reside in dynamically young groups, whereas jet systems show no preference between spiral-rich and spiral-poor group environments. The mechanical power of the jet sources in the low-richness sample groups is estimated to be ∼1042–1044 erg s−1 with their black hole masses ranging between 2 × 108 and 5 × 109 M⊙. We confirm previous findings that while radio jet sources tend to be associated with more massive black holes, black hole mass is not the decisive factor in determining jet activity or power.
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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 | 0.003 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".