Aims: We investigate the role of the second synchrotron self-Compton (SSC)
photon generation to the multiwavelength emission from the compact regions of
sources that are characterized as misaligned blazars. For this, we focus on the
nearest high-energy emitting radio galaxy Centaurus A and we revisit the
one-zone SSC model for its core emission. Methods: We have calculated
analytically the peak luminosities of the first and second SSC components by,
first, deriving the steady-state electron distribution in the presence of
synchrotron and SSC cooling and, then, by using appropriate expressions for the
positions of the spectral peaks. We have also tested our analytical results
against those derived from a numerical code where the full emissivities and
cross-sections were used. Results: We show that the one-zone SSC model cannot
account for the core emission of Centaurus A above a few GeV, where the peak of
the second SSC component appears. We, thus, propose an alternative explanation
for the origin of the high energy (≳0.4 GeV) and TeV emission, where
these are attributed to the radiation emitted by a relativistic proton
component through photohadronic interactions with the photons produced by the
primary leptonic component. We show that the required proton luminosities are
not extremely high, e.g. ∼1043 erg/s, provided that the injection
spectra are modelled by a power-law with a high value of the lower energy
cutoff. Finally, we find that the contribution of the core emitting region of
Cen A to the observed neutrino and ultra-high energy cosmic-ray fluxes is
negligible.Comment: 12 pages, 6 figures, 3 tables, accepted for publication in A&
