Radio core dominance of Fermi/LAT-detected AGNs

We present a sample of 4388 AGNs with available radio core-dominance parameters-defined as the ratio of the core flux densities to the extended ones, R=S_core_/S_ext._ - which includes 630 Fermi-detected AGNs from the fourth source catalog (4FGL) of the Fermi Large Area Telescope (Fermi/LAT); the rest are non-Fermi-detected AGNs. In our sample, 584 blazars are Fermi-detected and 1310 are not. The sample also contains other subclasses, such as Seyferts, Fanaroff-Riley I/II galaxies, and normal galaxies. We investigate various properties of the Fermi-detected and non-Fermi-detected AGNs by using core-dominance parameters, capitalizing on a previous study which showed that R is a good indicator of beaming. We then calculate radio spectral indices for the whole sample, and adopt {gamma}-ray-photon indices for the Fermi AGNs from the 4FGL catalog to discuss the properties of different subclasses. We obtain a relation between the core-dominance parameters and the radio spectral indices for both Fermi and non-Fermi sources, assuming a two-component model in the radio band. Our previous study ruled out the assumption that the core-dominance parameters and radio spectral indices are quite different for different AGN subclasses. This holds not only for Fermi sources but also for non-Fermi sources. In particular, R is, on average, greater for the former AGNs than for the latter. In this study, we enlarge our sample with available values of R to 4388 AGNs, and the obtained conclusions are consistent with our previous study. We assume that the same two-component model holds for the {gamma}-ray band as for the radio band, and therefore, adopt the same relation between the core-dominance parameters and the {gamma}-ray-photon indices for Fermi AGNs. Our fitting results indicate that the {gamma}-ray emissions of Fermi blazars originate mainly from the jet, and therefore, we conclude that the Fermi blazars are beamed.

Identifier
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/VIII/108
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/VIII/108
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=VIII/108
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/VIII/108
Provenance
Creator Pei Z-Y.; Fan J.-H.; Bastieri D.; Yang J.-H.; Xiao H.-B.
Publisher CDS
Publication Year 2020
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Galactic and extragalactic Astronomy; High Energy Astrophysics; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy