Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: XMM-Newton observations of the TeV BL Lac object PKS 2155--304 in 2006:
  signature of inverse Compton X-ray emission?
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math