Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The First VLT FORS1 spectra of Lyman-break candidates in the HDF-S and
  AXAF Deep Field   We report on low-resolution multi-object spectroscopy of 30 faint targets (R
\~ 24-25) in the HDF-S and AXAF deep field obtained with the VLT Focal
Reducer/low dispersion Spectrograph (FORS1). Eight high-redshift galaxies with
2.75< z < 4 have been identified. The spectroscopic redshifts are in good
agreement with the photometric ones with a dispersion $\sigma_z = 0.07$ at z<2
and $\sigma_z = 0.16$ at z>2. The inferred star formation rates of the
individual objects are moderate, ranging from a few to a few tens solar masses
per year. Five out of the eight high-z objects do not show prominent emission
lines. One object has a spectrum typical of an AGN. In the AXAF field two
relatively close pairs of galaxies have been identified, with separations of
8.7 and 3.1 proper Mpc and mean redshifts of 3.11 and 3.93, respectively.

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The categories of this paper are: cs
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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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: cond-mat
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The categories of this paper are: math
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph