Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A large-scale galaxy structure at z = 2.02 associated with the radio
  galaxy MRC0156-252   We present the spectroscopic confirmation of a structure of galaxies
surrounding the radio galaxy MRC0156-252 at z = 2.02. The structure was
initially discovered as an overdensity of both near-infrared selected z > 1.6
and mid-infrared selected z > 1.2 galaxy candidates. We used the VLT/FORS2
multi-object spectrograph to target ~80 high-redshift galaxy candidates, and
obtain robust spectroscopic redshifts for more than half the targets. The
majority of the confirmed sources are star-forming galaxies at z > 1.5. In
addition to the radio galaxy, two of its close-by companions (< 6'') also show
AGN signatures. Ten sources, including the radio galaxy, lie within |z - 2.020
| < 0.015 (i.e., velocity offsets < 1500 km/s) and within projected 2 Mpc
comoving of the radio galaxy. Additional evidence suggests not only that the
galaxy structure associated with MRC0156-252 is a forming galaxy cluster but
also that this structure is most probably embedded in a larger scale structure.

14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
2
The categories of this paper are: math