Quasar Viscosity Crisis

TL;DR

This paper discusses the limitations of standard viscous accretion disc models in explaining extreme variability in Active Galactic Nuclei and proposes 'extreme reprocessing' as a promising alternative mechanism.

Contribution

It introduces the concept of 'extreme reprocessing' to better explain AGN variability, challenging traditional viscous disc models.

Findings

Standard models struggle with observed variability

Extreme reprocessing can account for rapid changes

Proposes a new framework for AGN variability

Abstract

Recent observations of extreme variability in Active Galactic Nuclei have pushed standard viscous accretion disc models over an edge. "Extreme reprocessing" where an erratically variable central quasi-point source is entirely responsible for heating an otherwise cold and passive low-viscosity disc, may be the best route forward.