Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The relation between Lyman-alpha absorbers and gas--rich galaxies in the
  local universe   We use high-resolution hydrodynamical simulations to investigate the spatial
correlation between weak (N(HI) <10^{15} cm^{-2}) Ly-alpha absorbers and
gas-rich galaxies in the local universe. We confirm that Ly-alpha absorbers are
preferentially expected near gas-rich galaxies and that the degree of
correlation increases with the column density of the absorber. The real-space
galaxy auto-correlation is stronger than the cross-correlation (correlation
lengths r_{0,gg}=3.1 \pm 0.1 Mpc/h and r_{0,ag}=1.4 \pm 0.1 Mpc/h,
respectively), in contrast with the recent results of Ryan-Weber (2006, RW06),
and the auto-correlation of absorbers is very weak. These results are robust to
the presence of strong galactic winds in the hydrodynamical simulations. In
redshift-space a further mismatch arises since at small separations the
distortion pattern of the simulated galaxy-absorber cross-correlation function
is different from the one measured by RW06. However, when sampling the
intergalactic medium along a limited number of lines-of-sight, as in the real
data, uncertainties in the cross correlation estimates are large enough to
account for these discrepancies. Our analysis suggests that the statistical
significance of difference between the cross-correlation and auto-correlation
signal in current datasets is ~ 1-sigma only.

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The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin