Cd. Dermer et al., NONTHERMAL COMPTON AND SYNCHROTRON PROCESSES IN THE JETS OF ACTIVE GALACTIC NUCLEI, The Astrophysical journal. Supplement series, 109(1), 1997, pp. 103-137
We present the basic equations for calculating the time-dependent rece
ived spectral flux from the optically thin emissivities produced by te
mporally evolving, nonthermal electrons losing energy in a relativisti
cally moving blob of plasma located at cosmological distances. Ionizat
ion, bremsstrahlung, Compton, and synchrotron energy losses of the ele
ctrons are considered. These equations are used to derive and calculat
e the received spectral fluence produced by instantaneously injected n
onthermal electrons that also scatter photons from an isotropic extern
al monochromatic radiation held in the Thomson regime of scattering. T
he derivation of the fluences is restricted to the regime where either
synchrotron losses or Thomson losses with photons of the external rad
iation field dominate the electron energy loss rate. We also derive ap
proximate expressions for the synchrotron and synchrotron self-Compton
fluence. Beaming factors for thin-target and thick-target models of t
he electron distributions are derived. We show that ionization energy
losses of relativistic electrons on the background thermal plasma of t
he blob can give Comptonized gamma-ray fluence spectra with spectral b
reaks Delta alpha much greater than 0.5. If only,Thomson and synchrotr
on losses are important, spectral breaks much greater than 0.5 are als
o possible if electrons are injected with a low-energy cutoff or if a
''snapshot'' of the spectral flux is measured over a time interval muc
h less than the interval during which electrons cool. The important ob
servational quantities for testing Compton-scattering models of radio
galaxies and blazars are the bolometric luminosities in the radio/opti
cal synchrotron component and the X-ray/gamma-ray Compton component, w
hich approximately equal the peak values of the vF, spectral power flu
x or fluence. Numerical simulations of jet spectra are presented, show
ing the effects of different parameter values on the shapes of the syn
chrotron and Compton components. We derive straightforward predictions
for the simplest external Compton and synchrotron self-Compton models
from the analytic expressions for the spectra. The results are applie
d to quasi-simultaneous observations of 3C 279 at two different epochs
, showing that this behavior can be understood if the blazar radiation
results from electrons that Compton-scatter externally produced photo
ns in outflowing blobs with different bulk Lorentz factors. Fits to qu
asi-simultaneous observations of 3C 273 and quiescent and flaring stat
es of Mrk 421 are also presented.