Speaker
Zhiyuan Pei
(PD)
Description
I would like to present our previous work on the radio core dominance in Fermi blazars. We compiled a sample of 4437 sources with available radio core-dominance parameters defined as the ratio of the core flux densities to extended ones, namely, R = Score/Sext., which includes 696 Fermi-detected sources respect to the catalog of FL8Y, the first eight years of science data from the Fermi Gamma-ray Space Telescope mission, and the rest of them are non-Fermi-detected sources. In our sample, 636 blazars are Fermi-detected and 1294 are not, and also consists of other subclasses such as Seyfert, Fanaroff-Riley I/II and normal galaxies. We investigate various different properties between Fermi-detected sources and non-Fermi-detected ones by using the core-dominance parameters as the previous study has shown that R is a good indication of beaming effect.
We then calculate the radio spectral indices for whole sample and adopt γ-ray photon indices for Fermi sources from FL8Y catalog for discussing their different performances on different subclasses, and obtain the relation between core-dominance parameters and radio spectral indices for both Fermi and non-Fermi sources according to the two components model on radio band, which are consistent with our previous study.
We found that the core-dominance parameters and radio spectral indices are quite different for different subclasses of AGNs, not only for Fermi sources but also non-Fermi sources, particularly, R for the former ones is averagely higher than later ones. We also adopt the same relation on core-dominance parameters and γ-ray photon indices for Fermi sources by taking the same assumption with two components model on γ-ray band, and obtain the fitting results indicating that the γ-ray emissions of Fermi blazars are mainly from the core component, which is perhaps associated with the beaming effect. Therefore, Fermi blazars are beamed.
Primary author
Zhiyuan Pei
(PD)
Co-authors
Denis Bastieri
(PD)
Prof.
Junhui Fan
(University of Guangzhou)
