A brief (blazar oriented) overview on topics for multi-wavelength observations with TeV photons

Abstract

Multi-wavelength observations with TeV photons are an essential diagnostic tool to study the physics of TeV sources. The complex variability of blazars, however (timescales from years down to minutes, with different patterns and SED behaviours), requires a great effort on simultaneous campaigns, which should be performed possibly over several days. Spectral information is essential, and now with the new TeV and X-ray telescopes it can be obtained on timescales less than one hour. The insights from such observations can be tremendous, since recent results have shown that the X-ray and TeV emissions do not always follow the same behaviour, and flares can have different relations between rise and decay times. Unfortunately, the strong pointing constraints of XMM do not allow the full use of this satellite simultaneously with ground telescopes.