Bibcode
Falomo, R.; Ghisellini, G.; Maraschi, L.; Pian, E.; Sambruna, R. M.; Treves, A.; Scarpa, R.
Referencia bibliográfica
Advances in Space Research (ISSN 0273-1177), vol. 15, no. 5, p. (5)69-(5)72
Fecha de publicación:
5
1995
Número de citas
0
Número de citas referidas
0
Descripción
Simultaneous UV and X-ray observations of the blazar PKS 0521-365 are
combined with radio, IR, optical and gamma-ray data taken at different
epochs to study the overall emission from 109 to
1023 Hz. The energy distribution declines from the IR to the
UV range (alpha sub(opt-UV)=1.4 +/- 0.1), but hardens at higher
frequencies. The remarkably flat X-ray spectrum (energy index alpha=0.68
+/- -0.12 in the range 0.2-7 keV) suggests a significant contribution by
the inverse Compton process in this band. This is supported by the
detection of the source in gamma-rays by the Energy Gamma Ray Experiment
Telescope (EGRET) experiment. The full radio-to-gamma-ray energy
distribution is discussed. Various arguments indicate that the jet is
not closely aligned with the line of sight (theta approximately 30 deg),
implying that the observed radiation is weakly boosted. This allows a
direct estimate of the importance of different sources of photons
available for upscattering. We conclude that in this source the
synchrotron photons are likely to be the seeds for the inverse Compton
process.