Bibcode
Prieto, M. A.; Reunanen, J.; Tristram, K. R. W.; Neumayer, N.; Fernandez-Ontiveros, J. A.; Orienti, M.; Meisenheimer, K.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 402, Issue 2, pp. 724-744.
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2
2010
Citations
101
Refereed citations
93
Description
Spectral energy distributions (SEDs) of the central few tens of parsec
region of some of the nearest, most well-studied, active galactic nuclei
(AGN) are presented. These genuine AGN-core SEDs, mostly from Seyfert
galaxies, are characterized by two main features: an infrared (IR) bump
with the maximum in the 2-10μm range and an increasing X-ray spectrum
with frequency in the 1 to ~200keV region. These dominant features are
common to Seyfert type 1 and 2 objects alike. In detail, type 1 AGN are
clearly distinguished from type 2 by their high spatial resolution SEDs:
type 2 AGN exhibit a sharp drop shortwards of 2μm, with the optical
to UV region being fully absorbed; type 1s instead show a gentle 2μm
drop ensued by a secondary, partially absorbed optical to UV emission
bump. On the assumption that the bulk of optical to UV photons generated
in these AGN is reprocessed by dust and re-emitted in the IR in an
isotropic manner, the IR bump luminosity represents >~70 per cent of
the total energy output in these objects, and the second energetically
important contribution is the high energies above 20keV.
Galaxies selected by their warm IR colours, i.e. presenting a relatively
flat flux distribution in the 12-60μm range, have often being
classified as AGN. The results from these high spatial resolution SEDs
question this criterion as a general rule. It is found that the
intrinsic shape of the infrared SED of an AGN and inferred bolometric
luminosity largely depart from those derived from large aperture data.
AGN luminosities can be overestimated by up to two orders of magnitude
if relying on IR satellite data. We find these differences to be
critical for AGN luminosities below or about
1044ergs-1. Above this limit, AGN tend to dominate
the light of their host galaxy regardless of the integration aperture
size used. Although the number of objects presented in this work is
small, we tentatively mark this luminosity as a threshold to identify
galaxy-light-dominated versus AGN-dominated objects.
Related projects
The Central PARSEC of Galaxies using High Spatial Resolution Techniques
PARSEC is a multi-wavelength investigation of the central PARSEC of the nearest galaxies. We work on black-hole accretion and its most energetic manifestations: jets and hot spots, and on its circumnuclear environment conditions for star formation. We resort to the highest available angular resolution observations from gamma-rays to the centimetre
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