BL Lac Objects: Laboratories to study the environment and properties of   emitting particles in relativistic jets
  We report the variation of the spectral energy distribution (SED) of blazars as a function of source activity, based on available, simultaneous multi-wavelength (MWL) observations of BL Lac objects. We use a fully automatized \c{hi}2 minimization procedure, instead of the commonly used eye-ball fit, to model the data sets with a one-zone Synchrotron-Self-Compton (SSC) model. The obtained SSC parameters are then analyzed as a function of source luminosity, and the correlation between parameters is shown. Possibilities of improving the present observational and modeling status of BL Lac objects are also discussed. 
Nijil Mankuzhiyil, Stefano Ansoldi, Massimo Persic, Fabrizio Tavecchio
astro-ph.CO