Extreme blazars
arXiv:astro-ph/9812202 · doi:10.1016/S0927-6505(99)00018-3
Abstract
The recent Cherenkov telescope observations and detections of the BL Lac objects Mkn 421, Mkn 501, 1ES 2344+514, PKS 2155--304 and possibly 1ES 1959+658 have shown that there exists a subclass of BL Lac objects emitting a substantial fraction of their power between the GeV and the TeV bands. These are the sources whose synchrotron spectrum peaks, in a $ν$--$νF_ν$ representation, in the EUV or X-ray band. Here I suggest that even more extreme BL Lacs can exist, whose synchrotron spectrum peaks in the MeV band. These sources should emit a substantial fraction of their power in the TeV band by the inverse Compton process. Limits to the maximum possible emitted frequencies are discussed.
15 pages, 6 figures, invited paper at the VERITAS workshop on TeV Astrophysics of Extragalactic Objects