Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unveiling the central parsec region of an AGN: the Circinus nucleus in
  the near infrared with the VLT   VLT J- to M\p-band adaptive optics observations of the Circinus Galaxy on
parsec scales resolve a central bright Ks-band source with a FWHM size of 1.9
$\pm$ 0.6 pc. This source is only visible at wavelengths longward of 1.6 $\mu$m
and coincides in position with the peak of the [Si VII]~2.48 $\mu$m coronal
line emission. With respect to the peak of the central optical emission, the
source is shifted by $\sim$ 0.15\arcsec (2.8 pc) to the south-east. Indeed, it
defines the vertex of a fairly collimated beam which extends for $\sim$ 10 pc,
and which is seen in both continuum light shortward of 1.6 $\mu$m and in
H$\alpha$ line emission. The source also lies at the center of a $\sim$ 19 pc
size [Si VII] ionization {\it bicone}.
  Identifying this source as the nucleus of Circinus, its size is compatible
with a putative parsec-scale torus. Its spectral energy distribution,
characterized by a prominent narrow peak, is compatible with a dust temperature
of 300 K. Hotter dust within a 1 pc radius of the center is not detected. The
AGN luminosity required to heat this dust is in the range of X-ray luminosities
that have been measured toward the central source. This in turn supports the
existence of highly obscuring material, with column densities of $10^{24}$
cm$^{-2}$, that must be located within 1 pc of the core.

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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom