The Central Engines of Narrow‐Line Seyfert 1 Galaxies
Bibliographic record
Abstract
It has been suggested that narrow-line Seyfert 1 galaxies (NLS1s) are evolutionarily young objects, powered by accretion onto central black holes that are significantly lower in mass than those found in typical broad-line Seyfert galaxies. We explore this hypothesis through the analysis of high spatial resolution, near-IR imaging data. By employing the correlation between black hole mass and host galaxy bulge luminosity, we determine the mean black hole mass for our sample to be, in solar units, ⟨log( M BH )⟩ = 7.9. Using the correlation between the size of the broad-line region and the monochromatic continuum luminosity, we obtain black hole mass estimates under the assumption that the emission-line gas is in virial equilibrium. The mean black hole mass derived from this relation is ⟨log( M BH )⟩ = 6.4. We explore possible causes for this discrepancy in M BH estimates and the ramifications for our understanding of the role played by NLS1s in AGN evolution. Because numerical simulations constrain the start of the AGN duty cycle to a time shortly after a gravitational interaction, we examine the morphology and near-IR bulge colors of the NLS1 sample for evidence of recent encounters. The mean bulge color is found to be redder than that of both a matched sample of nonactive galaxies and published estimates for broad-line Seyfert galaxies. The source of the unusual bulge colors may be an excess of flux, peaking at 2.2 μm, that has been detected near the centers of some NLS1s. No evidence is found for light asymmetries or an extra stellar component that would indicate NLS1s are young objects. Finally, we postulate that there may be some interesting lines of circumstantial evidence suggesting that secular processes may be relevant in NLS1s.
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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 | 0.000 |
| 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) | 0.004 | 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".