Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for a second component in the high-energy core emission from
  Centaurus A?   We report on an analysis of \fermi data from four year of observations of the
nearby radio galaxy Centaurus A (Cen A). The increased photon statistics
results in a detection of high-energy ($>\:100$ MeV) $\gamma$-rays up to 50 GeV
from the core of Cen A, with a detection significance of about 44$\sigma$. The
average gamma-ray spectrum of the core reveals evidence for a possible
deviation from a simple power-law. A likelihood analysis with a broken
power-law model shows that the photon index becomes harder above $E_b \simeq 4$
GeV, changing from $\Gamma_1=2.74\pm0.03$ below to $\Gamma_2=2.09\pm0.20$
above. This hardening could be caused by the contribution of an additional
high-energy component beyond the common synchrotron-self Compton jet emission.
A variability analysis of the light curve with 15-, 30-, and 60-day bins does
not provide evidence for variability for any of the components. Indications for
a possible variability of the observed flux are found on 45-day time scale, but
the statistics do not allow us to make a definite conclusion in this regards.
We compare our results with the spectrum reported by H.E.S.S. in the TeV energy
range and discuss possible origins for the hardening observed.

22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga