Radio core dominance of Fermi blazars

Pei, Z. Y.; Jiang, Fan; Liu, Yi; Yuan, Yu-Hai; Cai, Wei; Xiao, H. B.; Lin, Chao; Yang, Jiang-He

doi:10.1007/s10509-016-2822-0

Cited by 24 publications

(11 citation statements)

References 57 publications

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“…Pei et al (2020b) analysed a larger sample of 4 388 AGNs with available log R, 584 are Fermi/LAT-detected blazars from 4FGL, and obtained that the log R for Fermi blazars is higher than that for non-Fermidetected blazars. This is the evidence that the γ-ray emission is strongly beamed (Ghisellini et al 1993;Dondi & Ghisellini 1995;Fan et al 2013b;Pei et al 2016).…”

Section: Introductionmentioning

confidence: 70%

“…Pei et al (2020b) present a up-to-date largest catalogue of available core-dominance parameters R. We point out that R are quite different for diverse subclasses of AGNs, and particularly, Fermi blazars hold, on average, higher R than the non-Fermi blazars, indicating that the γ -emissions of Fermi blazars are from the jet and more Dopplerboosted. The γ -emission is strongly beamed (Fan et al 2009;Pei et al 2016Pei et al , 2020b.…”

Section: Discussionmentioning

confidence: 99%

“…Ghisellini et al (1993) expressed the core-dominance parameter as R = f δ 3+α for the sources with the jets directly pointing to the observer. Therefore, the coredominance parameter is statistically a good indicator for beaming effect (Urry & Padovani 1995;Fan 2003;Pei et al 2016Pei et al , 2019.…”

Section: Correlation Analysismentioning

confidence: 99%

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The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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Blazars are a subclass of active galactic nuclei with extreme observation properties, which is caused by the beaming effect, expressed by a Doppler factor ( $\delta$ ), in a relativistic jet. Doppler factor is an important parameter in the blazars paradigm to indicate all of the observation properties, and many methods were proposed to estimate its value. In this paper, we present a method following Mattox et al. to calculate the lower limit on $\gamma$ -ray Doppler factor ( $\delta_{\gamma}$ ) for 809 selected Fermi/LAT-detected $\gamma$ -ray blazars by adopting the available $\gamma$ -ray and X-ray data. Our sample included 342 flat-spectrum radio quasars (FSRQs) and 467 BL Lac objects (BL Lacs), out of which 507 sources are compiled with available radio core-dominance parameter (R) from our previous study. Our calculation shows that the average values of the lower limit on $\delta_{\gamma}$ for FSRQs and BL Lacs are $\left\langle\delta_{\gamma}|_{\textrm{FSRQ}}\right\rangle = 6.87 \pm 4.07$ and $\left\langle\delta_{\gamma}|_{\textrm{BL\ Lac}}\right\rangle=4.31 \pm 2.97$ , respectively. We compare and discuss our results with those from the literature. We found that the derived lower limit on $\delta_{\gamma}$ for some sources is higher than that from the radio estimation, which could be possibly explained by the jet bending within those blazars. Our results also suggest that the $\gamma$ -ray and radio regions perhaps share the same relativistic effects. The $\gamma$ -ray Doppler factor has been found to be correlated with both the $\gamma$ -ray luminosity and core-dominance parameter, implying that the jet is possibly continuous in the $\gamma$ -ray bands, and R is perhaps an indicator for a beaming effect.

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Section: Introductionmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

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The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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“…In the radio band, the ratio of the two components, R radio , is defined as the radio core-dominance parameter, i.e. R radio = L b /L unb (see Orr & 2 Pei et al Browne 1982;Fan et al 2011;Pei et al 2016Pei et al , 2019Pei et al , 2020c. This ratio can also be expressed as: R(φ) = flux density of beamed compact core flux density of unbeamed components , R ⊥ = R(90 • ), (1) where φ is the viewing angle between the line-of-sight and the motion direction of the approaching side of the compact core and R ⊥ refers to the ratio of the luminosity in the jet to the unbeamed luminosity when φ = 90 • .…”

Section: Introductionmentioning

confidence: 99%

“…Later, Pei et al (2016) compiled a sample of 169 γ-ray loud blazars from 3FGL (Acero et al 2015) with available radio core-dominance parameters (R radio ) and γ-ray photon indices (α ph γ ), and investigated a two-component model for the γ-ray emission. Pei et al (2016) obtained a correlation between α ph γ and R radio , as done for the radio band by Fan et al (2010),…”

Section: Introductionmentioning

confidence: 99%

Beamed and unbeamed emission of $γ$-ray blazars

Pei,

Fan,

Yang

et al. 2020

Preprint

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A two-component model of radio emission has been used to explain some radio observational properties of Active Galactic Nuclei (AGNs) and, in particular, of blazars. In this work, we extend the two-component idea to the γ-ray emission and assume that the total γ-ray output of blazars consists of relativistically beamed and unbeamed components. The basic idea leverages the correlation between the radio core-dominance parameter and the γ-ray beaming factor. To do so, we evaluate this correlation for a large sample of 584 blazars taken from the fourth source catalog of the Fermi Large Area Telescope (Fermi-LAT) and correlated their γ-ray core-dominance parameters with radio coredominance parameters. The γ-ray beaming factor is then used to estimate the beamed and unbeamed components. Our analysis confirms that the γ-ray emission in blazars is mainly from the beamed component.

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Further evidence of superluminal active galactic nuclei as γ‐ray sources

et al. 2020

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In our previous work in Xiao et al. (SCPMA, 2019, 62, 129811), we suggested that six superluminal sources could be γ‐ray candidates, and in fact, five of them have been confirmed in the fourth Fermi‐LAT source catalog (4FGL). In this work, based on the 4FGL, we report a sample of 229 Fermi detected superluminal sources (FDSs), including 40 new FDSs and 62 non‐FDSs. Thus, we believe that all superluminal sources should have γ‐ray emissions, and superluminal motion could also be a clue to detect γ‐ray emission from active galactic nuclei. We present a new approach of Doppler factor estimate through the study of the γ‐ray luminosity (Lγ) and of the viewing angle (ϕ).

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Radio core dominance of Fermi blazars

Cited by 24 publications

References 57 publications

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Beamed and unbeamed emission of $γ$-ray blazars

Further evidence of superluminal active galactic nuclei as γ‐ray sources

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