Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Identification of a high redshift cluster in the field of Q2345+007
  through deep BRIJK' photometry   This paper describes new results on the identification of the complex
gravita- tional lens responsible for the double quasar Q2345+007. A
gravitational shear field was detected recently about 45'' away from the QSO,
centered on an excess of faint blue galaxies. We present deep photometric data
in the near-IR (J & K'), which are used together with optical BRI photometry to
build spectral ener- gy distributions for all the objects, and to derive a
photometric redshift esti- mate by comparison with synthetic spectrophotometric
data. We propose a statis- tical method to analyse the distribution in z. An
excess of galaxies at z about 0.75 is detected in this field, with a 2D
distribution showing a maximum located at the center of the weak-shear field.
The z inferred for this overdensity (a distant cluster of galaxies) corresponds
to an absorption system in the spectrum of the quasar B. Most cluster-member
candidates at z=0.75 are undergoing a star- formation process or are burst
systems 1 to 3 Gyr old. We also discuss the exis- tence of other possible
excesses of galaxies at different z planes.

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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
35
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: nlin
14
The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: q-alg