Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gaseous Galactic Halos and QSO Absorption Line Systems   Recent observations have shown that (some) metal line absorption systems in
QSO spectra arise from gas in galactic halos with radii much larger than the
optical radii of galaxies. We show that the observed galaxy-absorber
connections are natural results of galaxy formation in hierarchical
cosmogonies, where galaxies form from gas cooling and condensation in dark
matter halos.

29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg