出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We present a summary on the update of 3C 273’s Database and on the analysis of the longterm
multi-wavelength variability of this bright quasar. The on-line database is now covering more
than 40 years of observations from radio to gamma-rays offering a unique view on the complex
variability properties of this active galactic nucleus. The amplitude and the maximum time scales
of the variations depend strongly on the frequency and show trends that are characteristic of the
underlying emission processes. The variability properties of the X-ray band imply the presence
of either two separate components (possibly a Seyfert-like and a blazar-like) or at least two parameters
with different timing properties to account for the X-ray emission below and above 20
keV. The dominant hard X-ray emission is most probably not due to electrons accelerated by the
shock waves in the jet as their variability does not correlate with the flaring millimeter emission,
but seems to be associated to long-timescale variations in the optical. This optical component is
consistent with being optically thin synchrotron radiation from the base of the jet and the hard
X-rays would be produced through inverse Compton processes (SSC and/or EC) by the same
electron population. We show evidence that this synchrotron component extends from the optical
to the near-infrared domain, where it is blended by emission of heated dust that we find to be
located within about 1 light-year from the ultraviolet source.
