The Extended Jet In AP Librae As The Source Of The VHE $\gamma$-ray
  Emission
  Most modeling attempts of blazars use a small emission zone located close to
the central black hole in order to explain the broad-band spectral energy
distribution. Here we present a case where additionally to the small region a
$>$kpc-scale jet is required to successfully reproduce the spectrum and
especially the TeV emission, namely the low-frequeny peaked BL Lac object AP
Librae detected in the TeV domain by the H.E.S.S. experiment. Given that other
parts of the spectral energy distribution follow the characteristics implied by
the source classification, the inverse Compton component spans 10 orders of
magnitude, which cannot be reproduced by the one-zone model. Additionally,
observational constraints in both the synchrotron and inverse Compton
compoenent strongly constrain the parameters of a self-consistent model ruling
out the possibility of TeV photon production in the vicinity of the galactic
center. We discuss the possibility that the TeV radiation is emitted by highly
energetic particles in the extended, arcsec-scale jet, which has been detected
at radio and X-ray energies. The slope of the jet X-ray spectrum indicates an
inverse Compton origin, and an extrapolation to higher energies coincides with
a break feature in the $\gamma$-ray band. Modeling the jet emission with
inverse Compton scattering of the cosmic microwave background results in an
excellent fit of the radio, X-ray and TeV emission. Implications will be
discussed, such as properties of the jet, acceleration scenarios, and
observations to test the model. If confirmed, large scale jets are able to
efficiently accelerate particles and to keep relativistic speeds up to
distances of several 100kpc.
