Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence that 50% of BALQSO Outflows Are Situated at Least 100 pc from
  the Central Source   The most robust way for determining the distance of quasar absorption
outflows is the use of troughs from ionic excited states. The column density
ratio between the excited and resonance states yields the outflow number
density. Combined with a knowledge of the outflow's ionization parameter, a
distance from the central source (R) can be determined. Here we report results
from two surveys targeting outflows that show troughs from S IV. One survey
includes 1091 SDSS and BOSS quasar spectra, and the other includes
higher-quality spectra of 13 quasars observed with the Very Large Telescope.
Our S IV samples include 38 broad absorption line (BAL) outflows, and four
mini-BAL outflows. The S IV is formed in the same physical region of the
outflow as the canonical outflow-identifying species C IV. Our results show
that S IV absorption is only detected in 25% of C IV BAL outflows. The smaller
detection fraction is due to the higher total column density ($N_H$) needed to
detect S IV absorption. Since R empirically anticorrelates with $N_H$ the
results of these surveys can be extrapolated to C IV quasar outflows with lower
$N_H$ as well. We find that at least 50% of quasar outflows are at distances
larger than 100 pc from the central source, and at least 12% are at distances
larger than 1000 pc. These results have profound implications for the study of
the origin and acceleration mechanism of quasar outflows and their effects on
the host galaxy.

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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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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: econ