Beaming Effect in Fermi Blazars

Jiang, Fan; Yang, Chaohe; Zhang, Jingyi; Tao, Hua; Liu, Yi; Qin, Yi-Ping; Huang, Yong

doi:10.1093/pasj/65.2.25

Cited by 34 publications

(17 citation statements)

References 61 publications

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“…Fan et al (2013aFan et al ( , 2014 also calculated the γ-ray Doppler factor for this source with adopting the data from 2FGL and obtained 5.99 and 5.62, respectively, both by setting T= 1 d. Our estimation here is higher than the results from Fan et al (2013b) or Fan et al (2014), since some input parameters for calculation are quite different from there, F 1 keV = 4.338 µJy, E γ = 3.13 GeV, and α X = 0.84 are adopted. Fan et al (2013b) and Fan et al (2014) both reported E γ = 3.54 which are similar with this paper but quite low F 1 keV were used, 1.340 µJy and 0.961 µJy presented in Fan et al (2013b) and Fan et al (2014), respectively, and thus led their low estimation of δ γ . From constraining the brightness temperature, Liodakis et al (2018) found the Doppler factor of 11.64 for 3C 279, this value is lower than the average value of their sample.…”

Section: More Implicationsmentioning

confidence: 71%

“…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: 72%

“…Beaming effect is mostly studied using the radio emission, which yields that the radio variability Doppler factor (δ var ) method should be perhaps an appropriate way to describe the blazars population and beaming effect (Fan et al 2009(Fan et al , 2013bLiodakis & Pavlidou 2015;Liodakis et al 2017a,b).…”

Section: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 99%

“…Blazars, as the most extreme subclass of AGNs with a radio-loud behaviour and a relativistic jet pointing towards the observer (Urry & Padovani 1995), are characterised by having large amplitude and rapid variability, superluminal motion, high polarisation, core-dominated non-thermal continuum, and γ-ray emission, etc. (Wills et al 1992;Fan & Xie 1996;Bai et al 1998;Romero et al 2002;Fan 2005;Fan et al 2011Fan et al , 2013bFan et al , 2016Ghisellini et al 2010;Abdo et al 2009;Abdo et al 2010b,c;Urry 2011;Marscher et al 2011;Nolan et al 2012;Yang, Fan, & Yuan 2012;Yang et al 2019;Gupta et al 2012;Acero et al 2015;Xiao et al 2019;Ajello et al 2020;Pei et al 2019Pei et al , 2020a. All of these properties are due to the relativistic beaming effect.…”

Section: Introductionmentioning

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: More Implicationsmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 72%

Section: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

Self Cite

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show abstract

“…For two variable data sets, , ( = 1, ), we use the linear fitting to analyze their correlations, = ( ± Δ ) + ( 0 ± Δ 0 ), where k is the slope, 0 is the intersection, is the Student's t probability, and n is the number of points in the data set. The Pearson's correlation coefficient r is expressed as [32][33][34]…”

Section: The Relations Between the Spectral Indices And Flux Densitiesmentioning

confidence: 99%

Relations between the Spectral Indices and Flux Densities of Eight Blazars

Yuan

2019

Advances in Astronomy

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Relations between the flux densities (F) and spectral indices (α) can help us analyze the emission process. In this paper, we choose 8 blazars (0235+164, 0430+052, 1156+295, 3C345, 1308+326, 1413+135, 3C454.3, and 1749+096) from the University of Michigan Radio Observatory (UMRAO) database to study the relations between the spectral indices (α) and flux densities at 14.5GHz (F14.5). The main results are the following. (1) There are strong anticorrelations between α and F14.5, with the correlation coefficient r in the range from -0.33 to -0.87. (2) The α-F14.5 distributions show elliptic appearance, which have been fitted by elliptic curves. (3) For most of the sources, the time intervals of α-F14.5 elliptic circle (Tc) are consistent with the quasi-periodicities calculated by the averaged light curves and spectral variances (PαF¯).

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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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Beaming Effect in Fermi Blazars

Cited by 34 publications

References 61 publications

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

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

Relations between the Spectral Indices and Flux Densities of Eight Blazars

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

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