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GAMMA-RAY
FLARES AND VLBI OUTBURSTS OF BLAZARS
Authors:
M.M. Romanova, and R.V.E. Lovelace
A model is developed for the time dependent electromagnetic - radio to
gamma-ray - emission of active galactic nuclei, specifically, the blazars, based on the
acceleration and creation of leptons at a propagating discontinuity or front of a
self-collimated Poynting flux jet. The front corresponds to a discrete relativistic jet
component as observed with very - long - baseline - interferometry (VLBI). Equations are
derived for the number, momentum, and energy of particles in the front taking into account
synchrotron, synchrotron-self-Compton (SSC), and inverse-Compton processes as well as
photon-photon pair production. The apparent synchrotron, SSC, and inverse Compton
luminosities as functions of time are determined. Predictions of the model are compared
with observations in the gamma, optical, and radio bands. The delay between the
high-energy gamma-ray flare and the onset of the radio is explained by self-absorption
and/or free-free absorption by external plasma. Two types of gamma-ray flares are
predicted, Compton dominated or SSC dominated, depending on the initial parameters in the
front. The theory is applied to the recently observed gamma-ray flare of the blazar PKS
1622-297 (Mattox et al. 1996). Approximate agreement of theoretical and observed light
curves is obtained for a viewing angle q obs ~ 0.1 rad, a black hole mass M
~ 3 *10^9
©, and a magnetic field at the base of the jet Bo ~ 10^3 G.
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