Doppler Factor Estimation for Fermi Blazars

Zhang, L. X.; Chen, Sina; Xiao, H. B.; Cai, J. T.; Fan, J. H.

doi:10.3847/1538-4357/ab9180

Cited by 42 publications

(63 citation statements)

References 59 publications

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“…Because we now have a larger sample, we can more accurately determine the dividing line on the ratio L Disk /L Edd between BL Lacs and FSRQs, and also confirm the idea that the blazars' divide occur for the alteration in accretion regime (Ghisellini et al , 2011. To do so, first step we search the references and collect the available BLR luminosity regarding our sample as many as possible, and finally we compile 184 sources with L BLR (4 HBLs+19 IBLs+14 LBLs+147 FSRQs), which 164 sources from paper Zhang et al (2020) and 20 from Chen & Gu (2019). Secondly, we calculate the disk luminosity L Disk .…”

Section: Resultsmentioning

confidence: 57%

“…We end up the discussion here. More detailed interpretation of Doppler effect and δ can be found in our previous papers (e.g., Fan et al 2009aFan et al , 2013aPei et al 2020b;Zhang et al 2020;Ye & Fan 2021).…”

Section: Doppler Factor δmentioning

confidence: 81%

“…However, it is difficult for us to determine this parameter since it is undetectable. Hence, some feasible methods need to be proposed (Ghisellini 1993;Lähteenmäki & Valtaoja 1999;Fan et al 2009a;Hovatta et al 2009;Liodakis et al 2018;Zhang et al 2020;Pei et al 2020b).…”

Section: Doppler Factor δmentioning

confidence: 99%

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The Estimation of Fundamental Physics Parameters for Fermi-LAT Blazars

Pei,

Fan,

Yang

et al. 2021

Preprint

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Aiming to delineate the physical framework of blazars, we present an effective method to estimate four important parameters based on the idea proposed by Becker & Kafatos (1995), including the upper limit of central black hole mass M , the Doppler factor δ, the distance along the axis to the site of the γ-ray production d (which then can be transformed into the location of γ-ray-emitting region R γ ) and the propagation angle with respect to the axis of the accretion disk Φ. To do so, we adopt an identical sample with 809 Fermi-LAT-detected blazars which had been compiled in Pei et al. (2020b). These four derived parameters stepping onto the stage may shed new light on our knowledge regarding γ-ray blazars. With regard to the paper of Becker & Kafatos (1995), we obtain several new perspectives, mainly in: (1) putting forward an updated demarcation between BL Lacs and FSRQs based on the relation between broad-line region luminosity and disk luminosity both measured in Eddington units, i.e., L disk /L Edd = 4.68 × 10 −3 , indicating that there are some differences between BL Lacs and FSRQs on the accretion power in the disk; (2) proposing that there is a so-called 'appareling zone', a potential transition field between BL Lacs and FSRQs where the changing-look blazars perhaps reside; (3) the location of γ-ray emission region is principally constrained outside the broad-line region, and for some BL Lacs are also away from the dusty molecular torus, which means the importance of emission components in the jet.

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Section: Resultsmentioning

confidence: 57%

Section: Doppler Factor δmentioning

confidence: 81%

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The Estimation of Fundamental Physics Parameters for Fermi-LAT Blazars

Pei,

Fan,

Yang

et al. 2021

Preprint

Self Cite

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“…Fortunately, many indirect methods have been proposed to estimate the Doppler factor, such as Doppler factor estimation from radio flux density variation or variability brightness temperature (Lähteenmäki and Valtaoja 1999;Fan et al 2009;Hovatta et al 2009;Liodakis et al 2018), from the combination between X-ray emissions and synchrotron Self-Compton (SSC) modal (Ghisellini et al 1993), from pair-production opacity in the high energy emission (Mattox et al 1993;Fan et al 2013Fan et al , 2014Pei et al 2020), from broadband SED fitting (Chen 2018). Recently, Zhang et al (2020) proposed a new method using both the γ-ray luminosity and BLR luminosity to estimate Doppler factor for a sample of 350 blazars. Meanwhile, based on the unification of BL Lacs and their parent population of Fanaroff & Riley type I (FRI) radio galaxies and Fanaroff & Riley type II with radio morphology (FRII-G) (Fanaroff and Riley 1974), Ye and Fan (2021) assumed that the intrinsic correlation between core luminosity and extended luminosity for BL Lacs is the same as that of their parent radio galaxies (FRI and FRII-G), then estimated the Doppler factor for a sample of 297 BL Lacs.…”

Section: Introductionmentioning

confidence: 99%

A study of Intrinsic $γ$-ray Emission for {\it Fermi}/LAT-detected BL Lacs

Ye¹,

Zeng²,

Yang³

et al. 2021

Preprint

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BL Lacs are one subclass of blazars with highly energetic γ-ray emission, which is strongly boosted by a relativistic beaming effect. The latest catalogue of the 10 years of Fermi/LAT data (Abdollahi et al. 2020) and the γ-ray Doppler factors in Pei et al. ( 2020) provide us with a large BL Lac sample to study their jet emission morphologies and intrinsic properties. In this paper, we collected a sample of 294 Fermi BL Lacs and probed the correlations between the γ-ray emissions and luminosity distances. Our analyses give following conclusions: (1) the observed γ-ray emissions are really boosted by the γ-ray Doppler factor, and the intrinsic γ-ray emissions are closely correlated with luminosity distances. (2) the morphology of jet emissions for HBLs may be continuous, while that for IBLs may be the case of a moving sphere in the γ-ray bands.

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“…The Doppler factor is important for emissions in BL Lacs, which is determined by velocity (β) and the viewing angle (θ): δ = [Γ(1 − β cos θ)] −1 , where Γ is the Lorentz factor, satisfying Γ = 1/ 1 − β 2 . Some methods were proposed to estimate the Doppler factor (Ghisellini et al 1993;Mattox et al 1993;Lähteemäki & Valtaoja 1999;Fan et al 2013;Chen 2018;Liodakis et al 2018;Zhang et al 2020). Ghisellini et al (1993) adopted the synchrotron self-Compton (SSC) model and assumed the synchrotron high frequency cutoff as 10 14 Hz to obtain the Doppler factors.…”

Section: Introductionmentioning

confidence: 99%

Unification of BL Lac objects, FR I and FR II(G) radio galaxies and Doppler factor Estimation for BL Lac Objects

Ye,

Fan

2021

Preprint

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In this work, we collected a sample of BL Lacs, FR I and FR II(G) radio galaxies with available core and extended emissions from published works to discuss the unified schemes and estimate the Doppler factor for BL Lacs. Wilcoxon rank-sum test and Kolmogorov-Smirnov test both suggest that the probabilities for the distribution of the extended luminosity of BL Lacs and that of FR I and FR II(G) radio galaxies to be from the same parent distribution are p WRS = 0.779 and p K−S = 0.326, suggesting they are unified. Based on this unified schemes, we propose to estimate the Doppler factors for BL Lacs. Comparing the Doppler factor estimated by the fitting/regression method with those for the common sources in the literatures, we found a good linear correlation for common sources.

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Doppler Factor Estimation for Fermi Blazars

Cited by 42 publications

References 59 publications

The Estimation of Fundamental Physics Parameters for Fermi-LAT Blazars

The Estimation of Fundamental Physics Parameters for Fermi-LAT Blazars

A study of Intrinsic $γ$-ray Emission for {\it Fermi}/LAT-detected BL Lacs

Unification of BL Lac objects, FR I and FR II(G) radio galaxies and Doppler factor Estimation for BL Lac Objects

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