Variability studies and modelling of the blazar PKS 2155-304 in the light of a decade of multi-wavelength observations

The variability of the high-frequency peaked BL Lac object PKS 2155-304 is studied using almost 10 years of optical, X-ray and gamma-ray data. Publicly available data have been gathered and analysed with the aim to characterize the variability and to search for lognormality or periodic behaviour. The optical and X-ray range follow a lognormal process; a hint for a periodicity of about approximate to 700 d is found in optical and in the high energy (100 MeV < E < 300 GeV) range. A one-zone, time-dependent, synchrotron self-Compton model is successfully used to reproduce the evolution with energy of the variability and the tentatively reported periodicity.