The gamma-ray Doppler factor determinations for a Fermi blazar sample

Fan, J. H.; Yang, Jiang-He; Liu, Yi; Zhang, Jingyi

doi:10.1088/1674-4527/13/3/002

Cited by 55 publications

(60 citation statements)

References 50 publications

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“…A slight higher than our present result if we choose T = 6 h and smaller while T = 48 h is considered (see also Fan et al 2014). For the sake of simplicity, we adopt T = 24 h in this paper for calculation as did in Dondi & Ghisellini (1995), Fan et al (2013a), and Fan et al (2014). Besides, the non-simultaneous observations will also result in some discrepancies.…”

Section: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 55%

“…This is consistent with Dondi & Ghisellini (1995), they found the average value δ γ ∼ 4.4, ranging from 1.3 to 11 for a sample of EGRET blazars. Fan et al (2013a) obtained an average value δ γ ∼ 7.22 for 138 γ-ray blazars and Fan et al (2014) also found the average value was ∼7.00 with regard to their sample.…”

Section: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 84%

“…In this paper, we estimate the lower limit on γ-ray Doppler factors for those γ-ray blazars following Mattox et al (1993) as did in Fan et al (2013aFan et al ( , 2014, probing their relations and shedding new light on the relativistic beaming effect of γ-ray loud blazars. The methodology is discussed in Section 2, while in Section 3 we describe the sample and results.…”

Section: Introductionmentioning

confidence: 92%

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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: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 55%

Section: Comparison With Other Doppler Factors In the Literaturementioning

confidence: 84%

Section: Introductionmentioning

confidence: 92%

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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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“…The calculation of γ-ray opacity Doppler factors is based on the requirement that the γ−ray emission region must be transparent to gamma rays (Mattox et al 1993;Fan et al 2013Fan et al , 2014. The process responsible for γ-ray absorption is pair production due to the interaction between γ-ray photons and X-ray photons.…”

Section: Gamma-ray Opacity Doppler Factorsmentioning

confidence: 99%

Population statistics of beamed sources – II. Evaluation of Doppler factor estimates

Liodakis

Pavlidou

2015

Mon. Not. R. Astron. Soc.

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In a companion paper we presented a statistical model for the blazar population, consisting of distributions for the unbeamed radio luminosity function and the Lorentz factor distribution of each of the BL Lac and Flat Spectrum Radio Quasar (FSRQ) classes. Our model has been optimized so that it reproduces the MOJAVE distributions of apparent speeds and redshifts when the appropriate flux limit is applied and a uniform distribution of jet viewing angles is assumed for the population. Here we use this model to predict the Doppler factor distribution for various flux-limited samples for which Doppler factors have been estimated in a variety of ways (equipartition, variability + equipartition, inverse Compton dominance) on a blazar-by-blazar basis. By comparing the simulated and data-estimated Doppler factor distributions in each case, we evaluate the different methods of estimating blazar Doppler factors. We find that the variability Doppler factors assuming equipartition are the ones in the best agreement with our statistical model, whereas the inverse Compton Doppler factor method is only suitable for FSRQs. In the case of variability Doppler factors, we find that while random errors are relatively low (∼ 30%), uncertainties are dominated by systematic effects. In the case of inverse Compton Doppler factors, random errors appear to dominate, but are significantly larger (∼ 60%).

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“…Blazars represent a very special subclass of active galactic nuclei (AGNs) with luminous brightness, rapid and high amplitude variability, high and variable polarization, superluminal motion, strong γ-ray emission, etc (Fan et al 2013, and references therein). In turn, blazars can be divided into two subclasses, namely flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs).…”

Section: Introductionmentioning

confidence: 99%

The lower limit of the Doppler factor for a Fermi blazar sample

Fan¹,

Bastieri²,

Yang³

et al. 2014

Res. Astron. Astrophys.

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We selected 457 blazars (193 flat spectrum radio quasars, 61 lowsynchrotron peaked blazars, 69 intermediate-synchrotron peaked blazars and 134 high-synchrotron peaked blazars) from the second Fermi-LAT catalog (2FGL) of γray sources, which have X-ray observations. We calculated the lower limits for their Doppler factors, δ γ , and compared the lower limits with the available Doppler factors and the apparent superluminal velocities in the literature.

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The gamma-ray Doppler factor determinations for a Fermi blazar sample

Cited by 55 publications

References 50 publications

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

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

Population statistics of beamed sources – II. Evaluation of Doppler factor estimates

The lower limit of the Doppler factor for a Fermi blazar sample

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