Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Discovery of a Luminous z=5.80 Quasar from the Sloan Digital Sky
  Survey   We present observations of SDSSp J104433.04--012502.2, a luminous quasar at
z=5.80 discovered from Sloan Digital Sky Survey (SDSS) multicolor imaging data.
This object was selected as an i'-band dropout object, with i*=21.8 +/- 0.2,
z*=19.2 +/- 0.1. It has an absolute magnitude M1450 = -27.2 (H_0 =50 km/s/Mpc,
q0 = 0.5). The spectrum shows a strong and broad Ly alpha emission line, strong
Ly alpha forest absorption lines with a mean continuum decrement D_A = 0.91,
and a Lyman Limit System at z=5.72. The spectrum also shows strong OI and SiIV
emission lines similar to those of quasars at z<= 5, suggesting that these
metals were produced at redshift beyond six. The lack of a Gunn-Peterson trough
in the spectrum indicates that the universe is already highly ionized at z ~
5.8. Using a high-resolution spectrum in the Ly alpha forest region, we place a
conservative upper limit of the optical depth due to the Gunn-Peterson effect
of tau < 0.5 in regions of minimum absorption. The Ly alpha forest absorption
in this object is much stronger than that in quasars at z<= 5. The object is
unresolved in a deep image with excellent seeing, implying that it is unlensed.
The black hole mass of this quasar is ~3 x 10^9 M_solar if we assume that it is
radiating at the Eddington luminosity and no lensing amplification, implying
that it resides in a very massive dark matter halo. The discovery of one quasar
at M_1450 < -27 in a survey area of 600 deg^2 is consistent with an
extrapolation of the observed luminosity function at lower redshift. The
abundance and evolution of such quasars can provide sensitive tests of models
of quasar and galaxy formation.

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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: cs
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The categories of this paper are: q-fin
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph