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Many Active Galactic Nuclei (AGN) are surrounded by gas which absorbs the radiation produced by accretion onto the central black hole and obscures the nucleus from direct view. The dust component of the gas greatly enhances the effect of radiation pressure above that for Thomson scattering so that an AGN which is sub-Eddington for ionized gas in the usual sense can appear super-Eddington for cold dusty gas. The radiation-pressure enhancement factor depends on the AGN spectrum but ranges between unity and about 500, depending on the column density. It means that an AGN for which the absorption is long-lived should have a column density N_H>5x10^23 lambda cm^-2, where lambda is its Eddington fraction L_bol/L_Edd, provided that N_H}>5x10^21 cm^-2. We have compared the distribution of several samples of AGN - local, CDFS and Lockman Hole - with this expectation and find good agreement. We show that the limiting enhancement factor can explain the black hole mass - bulge mass relation and note that the effect of radiation pressure on dusty gas may be a key component in the feedback of momentum and energy from a central black hole to a galaxy.
Recent mid-infrared interferometry observations of nearby active galactic nuclei (AGN) revealed that a significant part of the dust emission extends in the polar direction, rather than the equatorial torus/disk direction as expected by the traditiona
It is typically assumed that radiation pressure driven winds are accelerated to an asymptotic velocity of V ~ v_esc, where v_esc is the escape velocity from the central source. We note that this is not the case for dusty shells and clouds. Instead, i
In the ion acceleration by radiation pressure a transverse inhomogeneity of the electromagnetic pulse results in the displacement of the irradiated target in the off-axis direction limiting achievable ion energy. This effect is described analytically
The remarkable similarity between emission spectra of narrow line regions (NLR) in Seyfert Galaxies has long presented a mystery. In photoionization models, this similarity implies that the ionization parameter is nearly always the same, about U ~ 0.
Infrared interferometry of local AGN has revealed a warm (~300K-400K) polar dust structure that cannot be trivially explained by the putative dust torus of the unified model. This led to the development of the disk+wind scenario which comprises of a