Synchrotron Self-Compton Model for PKS 2155-304
Abstract
H.E.S.S. observed TeV blazar PKS 2155--304 in a strong flare state in 2006 July. The TeV flux varied on timescale as short as a few minutes, which sets strong constraints on the properties of the emission region. By use of the synchrotron self-Compton model, we found that models with the bulk Lorentz factor 100, the size of the emission region 1015 cm, and magnetic field 0.1 G explain the observed spectral energy distribution and the flare timescale a few minutes. This model with a large value of accounts for the emission spectrum not only in the TeV band but also in the X-ray band. The major cooling process of electrons/positrons in the jet is inverse Compton scattering off synchrotron photons. The energy content of the jet is highly dominated by particle kinetic energy over magnetic energy.