Broadband variability of TeV BL Lac objects

S Kaufmann,O Tibolla,S Wagner

doi:10.1051/epjconf/20136104016

Abstract

BL Lac objects provide a direct view on the high energetic jet and offer the possibility to study the emission processes and the particle acceleration in the jet because of their broad emission range over the whole electromagnetic spectrum up to TeV energies. The variability information gives a direct estimation of the maximum size of the emission region. Under the assumption of the synchrotron Self-Compton model, which is a good description of the spectral energy distribution of BL Lac objects, correlated variability is expected in the different wavebands. The broadband variability is presented for the TeV BL Lac objects PKS 2005-489, RGB J0152+017 and 1ES 0229+200.

Highlights

The emitted radiation of active galactic nuclei (AGN) covers several decades of frequencies
While the first generation of Cherenkov telescopes detected only some very bright TeV sources, the new generation of Imaging Atmospheric Cherenkov Telescopes allowed us to increase the number of TeV sources to more than 100 with around 30 − 40% of AGN
The majority of AGN detected at TeV energies belong to the class of BL Lac objects

Summary

Introduction

The emitted radiation of active galactic nuclei (AGN) covers several decades of frequencies. Some AGN can be detected at highest energies, in the GeV and TeV γ-ray regime. The majority of AGN detected at TeV energies belong to the class of BL Lac objects. BL Lac objects are known to be very variable in all detected wavebands. Every set of simultaneous observations give only a short inside in the actual state of the source. The spectral energy distribution (SED) of high frequency peaked BL Lac objects are generally characterized by two peaks which are located in the UV-X-ray and the GeV-TeV band, respectively. These are commonly interpreted in terms of leptonic models The broadband variability for the TeV BL Lac objects PKS 2005-489, RGB J0152+017 and 1ES 0229+200 is presented

The BL Lac object with a soft TeV spectrum

The BL Lac object with a low synchrotron peak frequency

Conclusions