出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The fast variations of flux observed at TeV energies during exceptionnal outbursts of Active Galactic Nuclei (AGN) impose strong constraints on the size and Doppler factor of the emitting region. One of the most dramatic series of TeV bursts, the giant flares of the blazar PKS 2155−304 observed by H.E.S.S. during July 2006, exhibits significant rise times as short as 3 minutes. Faster structures could not be measured because of the limited sampling rate, directly related to the sensivity of H.E.S.S. The next generation of Atmospheric Cherenkov Telescopes, represented by the Cherenkov Telescope Array (CTA), will lower the energy threshold and increase the sensitivity in the TeV energy range. We investigate the impact of these improvements and show that a gain of almost a decade on the sampling capabilities of CTA will be achieved, allowing the probe of shorter time scales. We simulate the behaviour of PKS 2155−304 at such time scales extending the Fourier properties characterized by H.E.S.S in a first case and assuming that the source does not vary more than already observed in a second case. We show that, for each case, CTA could detect variability below the minute time scale. The consequences of such an ultra fast variability on the Doppler factor of the emitting region would challenge the models of emission of TeV blazars.
