Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of Galaxy Selection Upon Lyman Alpha Absorber Identification   While it is possible to explain Lyman alpha absorber counts at low redshift
using gas which is associated with moderately extended galaxies (Linder 1997),
absorbers are often observed to be associated with galaxies at larger impact
parameters from quasar lines of sight than are expected from calculated galaxy
absorption cross sections in such absorber-galaxy models. However, a large
fraction of absorbers is expected to arise in lines sight through galaxies
which are low in luminosity and/or surface brightness, so that they are
unlikely to be detected in surveys for galaxies close to quasar lines of sight.
Given that it is impossible to be certain that any particular absorber has been
matched to the correct galaxy, I show that it is possible to simulate plots of
absorption covering factors around luminous galaxies which resemble observed
plots by assuming that absorption often originates in unidentified galaxies.

31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph