Optical Classification of BZG Objects from the BZCAT Blazar Catalog

Abstract

In the blazar catalog BZCAT the objects are divided into 4 types: BZB, BZQ, BZG, and BZU. In this paper BZG objects are studied in order to determine their physical nature. Of the 274 BZG objects, 150 have optical spectra in the SDSS spectroscopic catalog, for which a detailed spectral classification has been carried out. A radio study showed that these objects mostly (69%) have a flat radio spectrum with a spectral index less than ±0.5. Quasars predominate among these kinds of radio spectra. However, with increasing distance, on the average the radio spectrum becomes steeper.