The origin of TeV electrons in blazars

There is increasing observational evidence that relativistic particles of e nergies similar to 1 TeV provide a significant pressure component of the pl asma which powers at least some of the relativistic jets associated with AG N. Furthermore, observations of flares with duration similar to 15 min at T eV energies indicate that the associated electrons are accelerated to the r equired energies on these or shorter time scales, which are comparable to t he synchrotron loss time for the values of the magnetic fields thought pres ent in these jets. As such, they push the potential acceleration mechanisms to their limits and prompt us to examine the conditions under which it may be possible for hadronic processes to provide the electrons of the requisi te energies. Relativistic hadrons could presumably exist within the flow, h aving been accelerated efficiently near the compact object and then transpo rted along with it, releasing their energy by an instability due to p-gamma reactions once a well-defined threshold is reached. (C) 1999 Elsevier Scie nce B.V. All rights reserved.