Publications
of the
MPIfR Optical & Infrared Interferometry Group
Wittkowski, M., Duschl, W.J., Hofmann,
K.-H.,
Men'shchikov, A., and Weigelt, G.
Interferometric studies of nearby galactic centers
in: W.A. Traub
(ed.),
Interferometry for Optical Astronomy II, SPIE Conf. Vol. 4838
(2003)
Abstract.
We discuss the potential of interferometric studies of nearby galactic
nuclei
with long-baseline interferometric facilities. Information on the
morphology
of galactic centers has so far been limited to angular sizes
corresponding
to the diffraction limit of 6-10 m class telescopes. Optical and
near-infrared
interferometry could in principle be used to reach significantly higher
angular
resolution, but has so far only been used for bright objects due to the
small
collecting areas of existing interferometers. Right now, the first
interferometers
consisting of 8-10 m class telescopes are starting operations and,
hence,
will soon allow us for the first time to study galactic centers on
angular
scales which are of an order of magnitude smaller than ever before,
i.e.
on scales corresponding to baselines of up to 100 m. We discuss these
facilities and report on the observational techniques and strategies
which are relevant
for interferometric observations of these objects. We review imaging
results
of nearby galactic centers with highest angular resolution so far, with
an
emphasis on our bispectrum speckle interferometry studies of the core
of
the Seyfert galaxy NGC 1068. Employing these results, we analyze how
near-infrared
interferometry can discriminate between the different scenarios which
are
consistent with our current knowledge based on observations. In
particular, characteristic sizes of the circumnuclear dusty torus can
be derived with
higher precision, additional dust components and the inner part of the
jet
can be identified, and radiative transfer models of the torus can be
better
constrained. Furthermore, the flux contribution of central source
components
can be separated from those of the torus, and thus they can be modeled
in
more detail. These investigations may ultimately result in a refinement
of
the unification scheme of galactic nuclei.
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