Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on Particle Acceleration from the Diffuse Isotropic
  Gamma-Ray Background   Gamma rays trace accelerated particles, and the observed flux of
extragalactic gamma rays therefore constrains the global efficiency for
particle acceleration. Extragalactic jets in active galactic nuclei can account
for the gamma ray background if their particle acceleration efficiency
considerably exceeds ~ 18 per cent which would imply that particle acceleration
is an essential part of the thermodynamics in these sources.

4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th