Long-term monitoring of PKS 2155$-$304 with ATOM and H.E.S.S.: investigation of optical/$\gamma$-ray correlations in different spectral states

A. Abramowski, F. Aharonian, F. Ait Benkhali +225

In this paper we report on the analysis of all the available optical and very high-energy $\gamma$-ray ($>$200 GeV) data for the BL Lac object PKS 2155$-$304, collected simultaneously w…