The luminosity history of fading local quasars over 10 <sup>4 − 5</sup> years as observed by VLT-MUSE
Bibliographic record
Abstract
We present a comprehensive study of five nearby active galaxies featuring large (tens of kiloparsecs) extended emission-line regions (EELRs). The study is based on large-format, integral-field spectroscopic observations conducted with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT). The spatially resolved kinematics of the ionized gas and stellar components show signs of rotation, bi-conical outflows, and complex behavior likely associated with past interactions. An analysis of the physical conditions of the EELRs indicates that in these systems the active galactic nucleus (AGN) is the primary ionization source. Using radiative transfer simulations, we compared the ionization state across the EELRs to estimate the required AGN bolometric luminosities at different radial distances. Then, considering the projected light travel time, we reconstructed the inferred AGN luminosity curves. We find that all sources are consistent with a fading trend in intrinsic AGN luminosity by 0.2–3 dex over timescales of 40 000 to 80 000 years, with a time dependence consistent with previous studies of fading AGNs. These results support the hypothesis that most AGNs undergo significant fluctuations in their accretion rates over multiple timescales ranging from 10 000 to 1 000 000 years, as proposed by existing theoretical models. These results provide new insights into the transient phases of AGN activity on previously unexplored scales and their potential long-term impact on their host galaxies through various feedback mechanisms.
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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 | 0.001 |
| 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".