Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The Column Density Distribution and Continuum Opacity of the
  Intergalactic and Circumgalactic Medium at Redshift <z>=2.4
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph