Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A note on shock wave in the dark matter medium   Employing Newton's stellar balance equation and using the flat rotation
velocity of satellite galaxies, we have found the velocity of sound in the dark
matter medium. What is interesting is that the velocity of satellite galaxies
is very much larger than the velocity of sound in the dark matter medium. This
indicates that there will be shock wave in the dark matter medium due to the
supersonic movement of satellite galaxies.

22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph