  High-energy emission of extragalactic objects is known to take place in
relativistic jets, but the nature, the location, and the emission processes of
the emitting particles are still unknown. One of the models proposed to explain
the formation of relativistic ejections and their associated non-thermal
emission is the two-flow model, where the jets are supposed to be composed of
two different flows, a mildly relativistic baryonic jet surrounding a fast,
relativistically moving electron-positron plasma. Here we present the
simulation of the emission of such a structure taking into account the main
sources of photons that are present in active galactic nuclei (AGNs). We
reproduce the broadband spectra of radio-loud AGNs with a detailed model of
emission taking into account synchrotron and inverse-Compton emission by a
relativistically moving beam of electron-positron, heated by a surrounding
turbulent baryonic jet. We compute the density and energy distribution of a
relativistic pair plasma all along a jet, taking into account the synchrotron
and inverse-Compton process on the various photon sources present in the core
of the AGN, as well as the pair creation and annihilation processes. We use
semi-analytical approximations to quickly compute the inverse-Compton process
on a thermal photon distribution with any anisotropic angular distribution. The
anisotropy of the photon field is also responsible for the bulk acceleration of
the pair plasma through the "Compton rocket" effect, thus imposing the plasma
velocity along the jet. As an example, the simulated emerging spectrum is
compared to the broadband emission of 3C273. In the case of 3C273, we obtain an
excellent fit of the average broadband energy distribution by assuming physical
parameters compatible with known estimates.
