Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The XMM-Newton view of gamma-ray loud active nuclei   Notwithstanding the big efforts devoted to the investigation of the
mechanisms responsible for the high-energy (E>100 MeV) gamma-ray emission in
active galactic nuclei (AGN), the definite answer is still missing. The X-ray
energy band (0.4-10 keV) is crucial for this type of study, since both
synchrotron and inverse Compton emission can contribute to the formation of the
continuum. Within an ongoing project aimed at the investigation of the
gamma-ray emission mechanism acting in the AGN detected by the EGRET telescope
onboard CGRO, we firstly focused on the sources for which X-ray and optical/UV
data are available in the XMM-Newton public archive. The preliminary results
are outlined here.

32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ