Comparing 3C 120 jet emission at small and large scales

Zargaryan, Davit; Gasparyan, Sargis; Baghmanyan, Vardan; Sahakyan, N.

doi:10.1051/0004-6361/201731601

Cited by 33 publications

(30 citation statements)

References 59 publications

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“…We then obtain the light travel distance of c × t cool ≃ 0.15 − 9.0 kpc, which are shorter than the distance from the radio-core and even smaller than the size of knots. Therefore, the particles should be accelerated locally (see also in 3C 120; Zargaryan et al 2017).…”

Section: The Knotsmentioning

confidence: 99%

Jet Radiation Properties of 4C +49.22: from the Core to Large-scale Knots

Zhang

Yao

et al. 2018

ApJ

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4C +49.22 is a γ-ray flat spectrum radio quasar with a bright and knotty jet. We investigate the properties of the core and large-scale knots by using their spectral energy distributions (SEDs). Analyzing its Fermi /LAT data in the past 8 years, a long-term steady γ-ray emission component is found besides bright outbursts. For the core region, the γ-ray emission together with the simultaneous emission in the low-energy bands at different epochs is explained with the single-zone leptonic model. The derived magnetization parameters and radiation efficiencies of the radio-core jet decrease as γ-ray flux decays, likely indicating that a large part of the magnetic energy is converted to the kinetic energy of particles in pc-scale. For the large-scale knots, their radio-optical-X-ray SEDs can be reproduced with the leptonic model by considering the inverse Compton scattering of cosmic microwave background photons. The sum of the predicted γ-ray fluxes of these knots is comparable to that observed with LAT at ∼ 10 24 Hz of the steady γ-ray component, indicating that the steady γ-ray emission may be partially contributed by these large-scale knots. This may conceal the flux variations of the low-level γ-ray emission from the radio-core. The derived bulk Lorentz factors of the knots decrease along the distance to the core, illustrating as deceleration of jet in large-scale. The powers of the core and knots are roughly in the same order, but the jet changes from highly magnetized at the core region into particle-dominated at the large-scale knots.

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Section: The Knotsmentioning

confidence: 99%

Jet Radiation Properties of 4C +49.22: from the Core to Large-scale Knots

Zhang

Yao

et al. 2018

ApJ

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“…Then the flux slowly decreased and the data collected within 10 to 35 days were enough to reach 20 % uncertainty. A more detailed analysis of the origin of emission using multiwavelength data is presented in Zargaryan et al (2017). Cen A core: The changes observed in the γ-ray spectrum are shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Fermi-LAT observation of nonblazar AGNs

Sahakyan

Baghmanyan

Zargaryan

2018

A&A

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Context. Fermi-LAT has recently detected γ-ray emission from active galactic nuclei which do not show clear evidence for optical blazar characteristics or have jets pointing away from the observer (non-blazar AGNs). These are interesting γ-ray emitters providing an alternative approach to studying high energy emission processes. Aims. Investigation of the spectral and temporal properties of γ-ray emission from non-blazar AGNs using the recent Fermi-LAT observational data. Methods. The data collected by Fermi-LAT during 2008-2015, from the observations of 26 non-blazar AGNs, including eleven FRI and ten FRII radio galaxies/SSRQs and five NLSY1s are analyzed using the new PASS 8 event selection and instrument response function. Possible spectral changes above GeV energies are investigated with a detailed spectral analysis. Light curves generated with normal and adaptive time bins are used to study the γ-ray flux variability. Results. Non-blazar AGNs have a γ-ray photon index in the range of 1.84 − 2.86 and a flux varying from a few times 10 −9 photon cm −2 s −1 to 10 −7 photon cm −2 s −1 . Over long time periods, power-law provides an adequate description of the γ-ray spectra of almost all sources. Significant curvature is observed in the γ-ray spectra of NGC 1275, NGC 6251, SBS 0846+513 and PMN J0948+0022 and their spectra are better described by log-parabola or power-law with exponential cut-off models. The γ-ray spectra of PKS 0625-25 and 3C 380 show a possible deviation from a simple power-law shape, indicating a spectral cutoff around the observed photon energy of E cut = 131.2 ± 88.04 GeV and E cut = 55.57 ± 50.74 GeV, respectively. Our analysis confirms the previous finding of an unusual spectral turnover in the γ-ray spectrum of Cen A: the photon index changes from Γ = 2.75± 0.02 to 2.31± 0.1 at 2.35± 0.08 GeV. In the Γ − L γ plane, the luminosity of non-blazar AGNs is spread in the range of (10 41 − 10 47 ) erg s −1 , where the lowest luminosity have FRI radio galaxies (but typically appear with a harder photon index) and the highest-SSRQs/NLSY1s (with softer photon indexes). We confirm the previously reported short-timescale flux variability of NGC 1275 and 3C 120. The γ-ray emission from NLSY1s, 1H 0323+342, SBS 0846+513 and PMN J0948+0022, is variable, showing flares in short scales sometimes accompanied by a moderate hardening of their spectra (e.g., on MJD 56146.8 the γ-ray photon index of SBS 0846+513 was Γ = 1.73 ± 0.14). 3C 111, Cen A core, 3C 207, 3C 275.1, 3C 380, 4C+39.23B, PKS 1502+036 and PKS 2004-447 show a long-timescale flux variability in the γ-ray band.

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“…In this case, the bin width is defined by requiring a constant relative flux uncertainty, so the time bins are longer during low flux levels and narrower when the source is in flaring state. The light curve generated by this method is a powerful tool for investigation of the flux variations in short time scales and identification of flaring periods as well as it contains maximum possible information on the flux variation (e.g., see Gasparyan et al 2018;Sahakyan et al 2018;Zargaryan et al 2017;Baghmanyan et al 2017;Britto et al 2016;Rani et al 2013b).…”

Section: Fermi-lat Datamentioning

confidence: 99%

Modeling the Broadband Emission of 3C 454.3

Sahakyan

2021

Preprint

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The results of a long-term multiwavelength study of the powerful flat spectrum radio quasar 3C 454.3 using Fermi-LAT and Swift XRT/UVOT data are reported. In the 𝛾-ray band, Fermi-LAT observations show several major flares when the source flux was > 10 −5 photon cm −2 s −1 ; the peak 𝛾-ray flux above 141.6 MeV, (9.22 ± 1.96) × 10 −5 photon cm −2 s −1 observed on MJD 55519.33, corresponds to 2.15 × 10 50 erg s −1 isotropic 𝛾-ray luminosity. The analysis of Swift XRT and UVOT data revealed a flux increase, although with smaller amplitudes, also in the X-ray and optical/UV bands. The X-ray emission of 3C 454.3 is with a hard spectral index of Γ X = 1.16 − 1.75, and the flux in the flaring states increased up to (1.80 ± 0.18) × 10 −10 erg cm −2 s −1 . Through combining the analyzed data, it was possible to assemble 362 high-quality and quasi-simultaneous spectral energy distributions of 3C 454.3 in 2008-2018 which all were modeled within a one-zone leptonic scenario assuming the emission region is within the broad line region, involving synchrotron, synchrotron self-Compton and external Compton mechanisms. Such an extensive modeling is the key for constraining the underlying emission mechanisms in the 3C 454.3 jet and allows to derive the physical parameters of the jet and investigate their evolution in time. The modeling suggests that during the flares, along with the variation of emitting electron parameters, the Doppler boosting factor increased substantially implying that the emission in these periods has most likely originated in a faster moving region.

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Comparing 3C 120 jet emission at small and large scales

Cited by 33 publications

References 59 publications

Jet Radiation Properties of 4C +49.22: from the Core to Large-scale Knots

Jet Radiation Properties of 4C +49.22: from the Core to Large-scale Knots

Fermi-LAT observation of nonblazar AGNs

Modeling the Broadband Emission of 3C 454.3

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