AGN-starburst evolutionary connection : a physical interpretation based
  on radiative feedback
  Observations point towards a close connection between nuclear starbursts,
active galactic nuclei (AGN), and outflow phenomena. An evolutionary sequence,
starting from a dust-obscured ultra-luminous infrared galaxy and eventually
leading to an unobscured optical quasar, has been proposed and discussed in the
literature. AGN feedback is usually invoked to expel the obscuring gas and dust
in a blow-out event, but the underlying physical mechanism remains unclear. We
consider AGN feedback driven by radiation pressure on dust, which directly acts
on the obscuring dusty gas. We obtain that radiative feedback can potentially
disrupt dense gas in the infrared-optically thick regime, and that an increase
in the dust-to-gas fraction leads to an increase in the effective Eddington
ratio. Thus the more dusty gas is preferentially expelled by radiative
feedback, and the central AGN is prone to efficiently remove its own obscuring
dust cocoon. Large amounts of dust imply heavy obscuration but also powerful
feedback, suggesting a causal link between dust obscuration and blow-out. In
this picture, AGN feedback and starburst phenomena are intrinsically coupled
through the production of dust in supernova explosions, leading to a natural
interpretation of the observed evolutionary path.
