We calculate for the nearest active galactic nucleus ( AGN ) , Centaurus A , the flux of high energy cosmic rays and of accompanying secondary photons and neutrinos expected from hadronic interactions in the source .
We use as two basic models for the generation of ultrahigh energy cosmic rays ( UHECR ) shock acceleration in the radio jet and acceleration in the regular electromagnetic field close to the core of the AGN .
While scattering on photons dominates in scenarios with acceleration close to the core , scattering on gas becomes more important if acceleration takes place along the jet .
Normalizing the UHECR flux from Centaurus A to the observations of the Auger experiment , the neutrino flux may be marginally observable in a 1 km ^ { 3 } neutrino telescope , if a steep UHECR flux { d } N / { d } E \propto E ^ { - \alpha } with \alpha = 2.7 extends down to 10 ^ { 17 } eV .
The associated photon flux is close to or exceeds the observational data of atmospheric Cherenkov and \gamma -ray telescopes for \alpha \raise 1.29 pt \hbox { $ > $ \kern - 7.5 pt \raise - 4.73 pt \hbox { $ \sim $ } } 2 .
In particular , we find that already present data favour either a softer UHECR injection spectrum than \alpha = 2.7 for Centaurus A or a lower UHECR flux than expected from the normalization to the Auger observations .