The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

Leon-Tavares, J.; Chavushyan, V.; Lobanov, A. P.; Valtaoja, E.; Arshakian, T. G.

doi:10.1017/s1743921315001842

Cited by 3 publications

(2 citation statements)

References 16 publications

(19 reference statements)

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“…However, an increase of emission-line fluxes in blazars coinciding with the ejection of superluminal knots during major γ-ray events has been found in the quasar 3C 454.3 (León-Tavares et al 2013), which challenges our current understanding of the location of the broad-line region (BLR). Emission-line flares in close temporal proximity to prominent γ-ray flares have been found in several other γ-ray blazars, which suggests that the jet might provide additional photoionization of the BLR (Isler et al 2015;León-Tavares et al 2015). Moreover, the detection of VHE γ-rays up to 600GeV from several quasars (e.g., Aleksić et al 2011) calls into question the origin of γ-rays within the BLR located <1 pc from the BH, since such high-energy photons would then not be able to escape without pairproducing off the intense photon field.…”

Section: Introductionmentioning

confidence: 76%

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

Jorstad

Marscher

Morozova

et al. 2017

ApJ

331

499

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We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BLLacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. Approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5pc (projected) of the core, and knots in BLLacs tending to decelerate near the core. Using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. We calculate the intrinsic brightness temperatures of the cores, T b,int core , at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ∼30% of T b,int core measurements in the quasars and BLLacs deviate from equipartition values by a factor >10. This probably occurs during transient events connected with active states. In the Appendix, we briefly describe the behavior of each blazar during the period analyzed.

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Section: Introductionmentioning

confidence: 76%

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

Jorstad

Marscher

Morozova

et al. 2017

ApJ

331

499

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“…If the dominant exciting radiation instead were to arise in the accretion disc, we would not expect to see such a strong correlation between the synchrotron continuum and line flux: the only direct association of flare and superluminal knot production in the jet with an event in the accretion disc corresponds to a decrease in the optical-ultraviolet flux of the disc (in the radio galaxy 3C 120; Marscher et al 2018). Since the jet emission is expected to be highly beamed by a Doppler factor ∼ 20 , the association of variations in emission-line flux with beamed synchrotron radiation from the jet implies that the clouds responsible for these lines lie within ∼ 10 • of the jet axis, as proposed by León-Tavares et al (2015).…”

Section: Optical Spectra and Variability Of Broad Emission-line Cloudsmentioning

confidence: 88%

Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

Ларионов

Jorstad

Marscher

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report the results of decade-long (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) γ-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ-ray light curves correlate well, with no delay > ∼ 3 hours, implying general co-spatiality of the emission regions. The γ-ray-optical flux-flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz VLBA images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain γ-ray variability on very short time scales. The Mg II emission line flux in the 'blue' and 'red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands we find progressive delays of the most prominent light curve maxima with decreasing frequency, as expected from the frequency dependence of the τ = 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at ∼ 5 GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet.

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Multiwavelength Analysis and the Difference in the Behavior of the Spectral Features during the 2010 and 2014 Flaring Periods of the Blazar 3C 454.3

Amaya-Almazán

Chavushyan

Patiño-Álvarez

2020

ApJ

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Over the years, the flat-spectrum radio quasar 3C 454.3 has presented phases of very high activity (flares) in which the different wave bands increase their flux dramatically. In this work, we perform multiwavelength analysis from radio to gamma-rays and study the Mg ii λ2798 emission line and the UV Fe ii band from 2008 to 2018. We found that an increase in the 43 GHz flux density of the quasi-stationary component C coincides with the estimated time at which a superluminal blob ejected from the radio core (which caused the brightest flare of 2010) collides with the quasi-stationary component (at a projected distance of ∼4.6 pc from the radio core). The different behavior of the spectral index in the first (5000 < JD − 2,450,000 < 5600) and second (6600 < JD − 2,450,000 < 7900) flaring periods suggests changes in the physical conditions. The complex nature of the second period can be a result of a superposition of multiple events at different locations. The Mg ii line has an anticorrelation with the UV continuum while Fe ii correlates positively, except at the time of the brightest flare of 2010, when both have a strong response at high continuum luminosities. Our results suggest that the dominant gamma-ray emission mechanism for the first flaring period is external Compton. For the second flaring period the region emitting seed photons is co-spatial with that emitting gamma-rays. However, a study of the spectral energy distribution using a multizone jet emission model is required to confirm the nature of each significant flare during the second period.

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The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

Cited by 3 publications

References 16 publications

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

Multiwavelength Analysis and the Difference in the Behavior of the Spectral Features during the 2010 and 2014 Flaring Periods of the Blazar 3C 454.3

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