Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2016+112: A Gravitationally Lensed Type-II Quasar   A single-screen model of the gravitational lens system 2016+112 is proposed,
that explains recent Hubble Space Telescope} (HST) infrared (NICMOS-F160W)
observations and new high-resolution European VLBI Network (EVN) 5-GHz radio
observations, presented in this paper. In particular, we find that a massive
`dark' structure at the lens position, previously suggested by X-ray, optical
and spectroscopic observations of the field around 2016+112, is not necessarily
required to accommodate the strong lensing constraints. A massive structure to
the north-west of the lens system, suggested from a weak-lensing analysis of
the field, is included in the model. The lensed source is an X-ray bright
active galaxy at z=3.273 with a central bright optical continuum core and
strong narrow emission lines, suggestive of a type-II quasar. The EVN 5-GHz
radio maps show a radio-jet structure with at least two compact subcomponents.
We propose that the diamond caustic crosses the counter-jet of the radio
source, so that part of the counter-jet, host galaxy and narrow-line emission
regions are quadruply imaged. The remainder of the radio source, including the
core, is doubly imaged. Our lens model predicts a very high magnification
(mu~300) at the bightness peaks of the inner two radio components of complex C.
If the jet exhibits relativistic velocities on micro-arsecond scales, it might
result in apparent hyperluminal motion. However, the lack of strong radio
variability and the peaked radio spectrum imply that these motions need not be
present in the source. Our model furthermore implies that the optical spectrum
of C' can only show features of the AGN and its host galaxy.

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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: math-ph