Radiation-regulated unification ties AGN classes to merger-driven black hole growth phases
Ricci integrates orientation-based and evolutionary unification into a single scheme that connects nuclear structures to galaxy-scale processes and black-hole growth across cosmic time. The review highlights how radiative feedback and mergers drive transitions between observational classes, resolving tensions with changing-look AGN and redshift-dependent obscuration trends. Limitations remain in the absence of new observational datasets and quantitative predictions for next-generation facilities.
The chapter reviews the canonical dusty torus geometry and extends it with the radiation-regulated framework in which accretion luminosity clears or rebuilds obscuring material on 10^4-10^5 yr timescales. This couples directly to merger-triggered inflows that both fuel rapid Eddington growth and modulate the torus covering factor, explaining the observed rise in obscured fractions at z greater than 1.5. Changing-look AGN are reframed as brief feedback episodes rather than purely geometric reorientations, consistent with multi-epoch spectroscopic surveys showing 1-3 percent transition rates in luminous quasars.
JWST: Mid-infrared spectra of 200 X-ray selected AGN at 1.5 less than z less than 3 will detect a 25 percent drop in average torus covering factor above L_bol = 10^45 erg/s within 24 months of Cycle 3 data release.
Sources (3)
- [1]Primary Source(https://arxiv.org/abs/2606.12511)
- [2]Supporting Source(https://ui.adsabs.harvard.edu/abs/2015ApJ...803...26N)
- [3]Supporting Source(https://ui.adsabs.harvard.edu/abs/1993ARA%26A..31...473A)