Time-dependent modelling of PKS 2155-304 in a low state: one- or two-zone emission modelling?
Department of Astrophysics, Astronomy and Mechanics Faculty of Physics University of Athens Greece
Published online: 9 December 2013
One-zone radiation models have been widely used in modelling the steady-state multiwavelength (MW) spectra of blazars, having as main goal the determination of the physical conditions in the emitting region, such as the magnetic field strength, the species of radiating particles etc. Then, the results from onezone stationary modelling are often used as a stepping stone for studying flaring events. Here we show that the application of steady-state one-zone models on intrinsic variable sources, even when these are in a low state, can be misleading. Although the one-zone SSC and proton synchrotron models succeed in fitting the time-averaged MWspectrum, they cannot easily (or at all) reproduce the small amplitude multifrequency variability.We show that a two-component leptonic model addresses both spectral and temporal observations more successfully, albeit at the expense of more free parameters.
© Owned by the authors, published by EDP Sciences, 2013
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