Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Cosmic MeV Gamma-ray Background and Hard X-ray Spectra of Active
  Galactic Nuclei: Implications for the Origin of Hot AGN Coronae   The origin of the extragalactic gamma-ray background radiation at 1-10 MeV is
still unknown. Although the cosmic X-ray background (CXB) up to a few hundreds
keV can be accounted for by the sum of Active Galactic Nuclei (AGNs), current
models of AGN spectra cannot explain the background spectrum beyond ~1 MeV,
because of the thermal exponential cutoff of electron energy distribution
assumed in the models. Here we construct a new spectral model by calculating
the Comptonization process including nonthermal electrons, which are expected
to exist in an AGN hot corona if it is heated by magnetic reconnections. We
show that the MeV background spectrum can nicely be explained by our model,
when coronal electrons have a nonthermal power-law component whose total energy
is a few percent of the thermal component and whose spectral index is d(ln
N_e)/d(ln E_e) ~ -4. Although the MeV gamma-ray flux from such a component in
nearby AGN spectra is below the detection limit of past observations, it could
be detected by planned future MeV detectors. We point out that the amount of
the nonthermal component and its electron index are similar to those found for
electrons accelerated by magnetic reconnections in solar flares and the Earth
magnetosphere, giving a support to the reconnection hypothesis for the origin
of hot AGN coronae.

27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
16
The categories of this paper are: stat