Ben-Gurion University of the NegevAstrophysics and Cosmology GroupAstrophysics, Relativity, Cosmology, and Space Physics |
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Speaker: Jonathan Stern (Technion) June 26, 2013 Radiation Pressure Confinement in Active Galaxies
The
pressure from the radiation of active galactic nuclei (AGN) can exceed
the typical gas pressure in the interstellar medium by many orders of
magnitude. We show that in luminous AGN, this radiation pressure likely
confines the ionized gas in the host galaxy. Radiation pressure
confinement produces a unique hydrostatic solution, which is
independent of the boundary conditions. The gas density within each
slab scales as the distance from the nucleus to the power of -2. Thus,
the AGN radiation pressure sets the density of the illuminated gas in
the host galaxy. We show that this density vs. distance relation is
observed over a dynamical range of ~10^4 in distance and ~10^8 in gas
density. The unique hydrostatic solution implies a highly ionized X-ray
emitting surface, and a lower ionization inner layer which emits
optical lines. This slab structure can explain the observed
overlap of the extended X-ray and optical line emission. We further
support radiation pressure confinement by comparing the predicted
ratios of the narrow lines strength with available observations.
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Last updated
by Uri Keshet,
2013 |