Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The jet of the BL Lacertae object PKS 2201+044: MAD near-IR adaptive
  optics observations and comparison with optical, radio and X-ray data   Relativistic jets are a common feature of radio loud active galactic nuclei.
Multifrequency observations are a unique tool to constrain their physics.
  We report on a detailed study of the properties of the jet of the nearby BL
Lac object PKS 2201+044, one of the rare cases where the jet is detected from
radio to X-rays. We use new adaptive optics near-IR observations of the source,
obtained with the ESO multi-conjugated adaptive optics demonstrator (MAD) at
the Very Large Telescope. These observations acquired in Ground-Layer Adaptive
Optics mode are combined with images previously achieved by HST, VLA and
Chandra to perform a morphological and photometric study of the jet. We find a
noticeable similarity in the morphology of the jet at radio, near-IR and
optical wavelengths. We construct the spectral shape of the main knot of jet
that appears dominated by synchrotron radiation. On the basis of the jet
morphology and the weak lines spectrum we suggest that PKS 2201+044 belongs to
the class of radio sources intermediate between FRIs and FRIIs.

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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex