Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Accretion by Galaxies   Both theory and observation indicate that galaxies like the Milky Way accrete
matter at the rate of a few Msun per year.

23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-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