Fermi Large Area Telescope View of the Core of the Radio Galaxy
  Centaurus A
  We present gamma-ray observations with the LAT on board the Fermi Gamma-Ray
Telescope of the nearby radio galaxy Centaurus~A. The previous EGRET detection
is confirmed, and the localization is improved using data from the first 10
months of Fermi science operation. In previous work, we presented the detection
of the lobes by the LAT; in this work, we concentrate on the gamma-ray core of
Cen~A. Flux levels as seen by the LAT are not significantly different from that
found by EGRET, nor is the extremely soft LAT spectrum
($\G=2.67\pm0.10_{stat}\pm0.08_{sys}$ where the photon flux is $\Phi\propto
E^{-\G}$). The LAT core spectrum, extrapolated to higher energies, is
marginally consistent with the non-simultaneous HESS spectrum of the source.
The LAT observations are complemented by simultaneous observations from Suzaku,
the Swift Burst Alert Telescope and X-ray Telescope, and radio observations
with the Tracking Active Galactic Nuclei with Austral Milliarcsecond
Interferometry (TANAMI) program, along with a variety of non-simultaneous
archival data from a variety of instruments and wavelengths to produce a
spectral energy distribution (SED). We fit this broadband data set with a
single-zone synchrotron/synchrotron self-Compton model, which describes the
radio through GeV emission well, but fails to account for the non-simultaneous
higher energy TeV emission observed by HESS from 2004-2008. The fit requires a
low Doppler factor, in contrast to BL Lacs which generally require larger
values to fit their broadband SEDs. This indicates the $\g$-ray emission
originates from a slower region than that from BL Lacs, consistent with
previous modeling results from Cen~A. This slower region could be a slower
moving layer around a fast spine, or a slower region farther out from the black
hole in a decelerating flow.
