Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Galaxy evolution in merging clusters: The passive core of the "Train
  Wreck" cluster of galaxies, A520
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
18
The categories of this paper are: econ