A study of the synchrotron component in the blazar spectral energy distributions

© Pleiades Publishing, Ltd., 2015. We study the synchrotron component of nonthermal radiation of blazars using the spectral energy distribution (SED). The sample contains a total of 877 blazars, including 423 flat-spectrum radio quasars (FSRQs), 361 BL Lac objects and candidates, and 93 blazars of uncertain type. Using the ASDC SED Builder Tool, we have made an estimation of the synchrotron peak frequency νspeak using archive data of different catalogs. The position of the synchrotron peak frequency was determined for 875 objects, which were further classified as follows: 611 low-synchrotron peaked (LSP) blazars (νspeak 14.5 Hz), 222 intermediate-synchrotron peaked (ISP) blazars (1014.5 s peak speak > 1016.5 Hz). For the FSRQs the average νspeak is 1013.4±1.0 Hz, for the BL Lac-type blazars it equals 1014.6±1.4 Hz. We found that νs peak values and the spectral flux density at 4.8 GHz form different distributions for two types of blazars—FSRQ and BL Lac— and for the radio-selected (RBLs) and x-ray-selected (XBLs) blazars. The distribution of νspeak values is broader for BL Lac objects than for FSRQs. There are no ultra-high-energy synchrotron-peak BL Lac objects (UHBLs, with νspeak > 1019 Hz) in our sample. We have found very-low-synchrotron peaked (VLSP) blazar candidates (with νspeak < 1013 Hz). Most of them are the FSRQs (41% of the total number) and only 9%are the BL Lac objects. Our results confirm the results of other authors, made on the samples with a significantly smaller number of objects