Issue |
A&A
Volume 425, Number 2, October II 2004
|
|
---|---|---|
Page(s) | 405 - 416 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20040546 | |
Published online | 21 September 2004 |
The impact of thermal gas in AGN jets on the low-frequency emission*
1
Institut für Theoretische Physik, Lehrstuhl IV, Ruhr-Universität Bochum, 44780 Bochum, Germany e-mail: ms@tp4.ruhr-uni-bochum.de
2
Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
Received:
29
March
2004
Accepted:
25
May
2004
We study the effect of non-relativistic, thermal matter in the jets of active galaxies (AGN) on the low-frequency non-thermal emission and the variability thereof. In matter-dominated jets, sizable quantities of gas should exist, in particular in the compression zones near the collision fronts that are an implicit ingredient of Fermi-type particle acceleration scenarios. Non-relativistic thermal gas in AGN jets noticably contributes to the optical depth at radio to infrared frequencies, and much less to the emission, with an efficiency that is strongly temperature-dependent. The observable flux of low-frequency emission is thus modulated by the temperature evolution of the thermal gas, and it can therefore display very complicated variability. For a particular particle energisation scenario we calculate the temperature evolution of the thermal plasma as well as the radiation transport of low-frequency emission, and thus derive simulated light curves at different frequencies and their typical correlation properties.
Key words: galaxies: active / plasmas
© ESO, 2004
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