Freiburg 2008 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 15: Astrophysics III

EP 15.10: Talk

Thursday, March 6, 2008, 16:45–17:00, KGI-Aula

Two zone SSC model for blazar jets — •Leonard Burtscher — Max-Planck-Institut für Astronomie, Heidelberg, Deutschland

One zone SSC models have had much success in explaining the overall spectral energy distributions of blazar jets. They cannot, however, explain some temporal signatures as they lack a profound modelling of the acceleration process. Instead they inject power-law distributed electrons which then cool and produce time-variability. Any spectral signatures of the time-dependence therefore can only arise from the cooling of particles -- not from the acceleration mechanism -- leaving the sometimes observed counter-clockwise 'spectral hysteresis' curves (i.e. spectral index plotted against intensity) unexplained.

In their model, Kirk et al. (1998) wanted to overcome this limitation by separating the blob region in two zones, a thin zone (thought to be around the shock), responsible for accelerating the electrons, and a larger `radiation zone' in which particles accumulate and radiate after they escaped from the `acceleration zone'. This model was restricted to synchrotron emission, however, with the high-energy part of the spectrum, thought to arise from Inverse Compton scattering, missing.

Here I present the Inverse Compton extension to this model. As expected, spectral hysteresis curves very similar to the ones in the synchrotron regime are also produced in the Inverse Compton branch. Comparisons with observational data are so far inconclusive but several possibilities to test the model will be pointed out.