Identification of extreme blazar candidates in X-ray catalogs.
Foffano L., Prandini E., Franceschini A., Doro M.
Blazars are active galactic nuclei with a jet pointing towards us. They are divided into subclasses depending on the peak frequency of the synchrotron emission. Some of these sources are extremely energetic and are classified as extreme blazars (EHBLs), with the emission extending up to several TeV. EHBLs are the ideal probes of the extragalactic background light and the nature of their emission is not completely understood. In order to increase the sample of EHBLs, we use X-ray--based selection criteria to propose new candidates to be observed with current generation of X-ray and very-high-energy telescopes.