Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Proximity Effect of QSO Metal Line Absorption Systems on Lyman
  $\alpha$ Forests   The proximity effect of metal line absorption systems in spectra of high
redshift quasars and quasar pairs is investigated through the distribution of
\Lyalpha forests. No strong proximity effect is found down to 500 km/sec away
from a metal line absorption system for lyman $\alpha$ clouds with
$13.3\le\log\NHI <13.8$ at a redshift of $\sim 3$. Its implication on
properties of high redshift galaxies and \Lyalpha clouds is discussed. More
high resolution spectra of high redshift quasars and pairs of quasars (whose
lines of sight are separated by $\sim 0.3h^{-1}$ to 1$h^{-1}$ Mpc) are needed
so that the proximity effect can be reliably determined for \Lyalpha clouds
with various $\NHI$ and down to a closer distance.

26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin