E. Pian et al., THE BROAD-BAND ENERGY-DISTRIBUTION OF THE MISALIGNED GAMMA-RAY BLAZARPKS-0521-365, The Astrophysical journal, 459(1), 1996, pp. 169-174
Simultaneous UV and X-ray observations of the blazar PKS 0521-365 are
combined with radio, IR, optical, and gamma-ray data taken at differen
t epochs to study the overall emission from 10(9) to 10(23) Hz. The fl
ux distribution declines from the IR to the UV range (alpha(opt-UV) =
1.4 +/- 0.1), but hardens at higher frequencies. The remarkably flat X
-ray spectrum (energy index alpha(X) = 0.68 +/- 0.12 in the range 0.2-
7 keV) suggests a significant contribution by the inverse Compton proc
ess in this band. This is supported by the detection of the source in
gamma-rays by the EGRET experiment. The full radio-to-gamma-ray energy
distribution is discussed. Various arguments suggest that the jet is
not closely aligned with the line of sight (theta similar to 30 degree
s), implying that the observed radiation is weakly boosted. This allow
s a direct estimate of the importance of different sources of photons
available for upscattering. We conclude that in this source the synchr
otron photons are likely to be the seeds for the inverse Compton proce
ss.