Classification of Blazars by Activity Types

Blazars are the most energetic sources in the Universe. They unify two major types of objects: BL Lac objects and Flat Spectrum Radio Quasars (FSRQ). So far, 3561 blazars are known from BZCAT v.5 catalogue. However, in BZCAT v.5 all blazars are grouped into four main classes, where extended radio sources and some unknown objects are added: BZB (BL Lac objects), BZQ (FSR Quasars), BZG (Blazar-like (BZQ-like) Galaxies) and BZU (Blazars of Unknown subtypes). There is no information about optical classification of these sources. We have accomplished optical classification for BZU and BZG sources, which have optical spectra from SDSS catalogue. Most of these sources had no optical class before or have changed their optical classification after our work. For some blazars, we obtained optical classes for the first time. In the current work we have done an overall optical investigation for all classes of blazars (BZB, BZQ, BZG and BZU). After the optical classification, some BZU sources, which have SDSS spectra, have changed to QSO (BZQ) or Galaxies (BZG). This way we give a better understanding of objects included in BZCAT v.5.