German Title: Hochaufgelöste Multifrequenzanalyse des Jets in 3C273
Translation of abstract (English)
The jet in 3C273 is one of only a few extragalactic optical synchrotron jets which are large and bright enough to be studied in detail. We present new broad-band observations of this jet at the unprecedented common resolution of 0.3' which have been obtained with the Very Large Array at radio and the Hubble Space Telescope at infrared, optical and ultraviolet wavelengths. These observations reveal a flattening of the high-frequency spectrum of the jet, a surprising feature which cannot be accounted for by any single-population synchrotron model. Both the observed flattening of the high-frequency spectrum and the X-ray emission from the jet can be explained by a model in which two distinct electron populations contribute to the jet's emission. We fit spatially resolved synchrotron spectra for the jet and determine the run of the maximum particle energy. The decrease of the maximum particle energy along the jet is much slower than expected from the observed synchrotron emission. We find no evidence for localised acceleration or loss sites. We show that relativistic beaming and/or sub-equipartition magnetic fields cannot remove the discrepancy between light-travel time along the jet and the shorter lifetime of electrons emitting optical synchrotron radiation. We consider this further evidence in favour of a distributed electron acceleration process.
|Supervisor:||Röser, Dr. Hermann-Josef|
|Date of thesis defense:||17 October 2001|
|Faculties / Institutes:||Service facilities > MPI for Astronomy|
|Controlled Keywords:||Jet <Astronomie>, Aktiver galaktischer Kern, Teilchenbeschleunigung, Synchrotronstrahlung|
|Uncontrolled Keywords:||Jet (astronomy), Active Galactic Nuclei , Particle acceleration , Synchrotron emission , Inverse Compton emission|