Nonthermal Compton and Synchrotron Processes in the Jets of Active Galactic Nuclei

Dermer, C. D.; Sturner, Steven J.; Schlickeiser, R.

doi:10.1086/312972

Cited by 164 publications

(196 citation statements)

References 30 publications

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“…Assuming that the specific flux of the flare follows a power law f ν ∝ ν −α , the ratio of inverse-Compton and synchrotron emission at fixed frequencies scales with f IC ν / f Syn ν ∝ (δ/B) 1 + α (Dermer et al 1997;Georganopoulos et al 2002), with δ the relativistic Doppler factor and B the average magnetic field in the emission region. Therefore, the H.E.S.S.…”

Section: Discussionmentioning

confidence: 99%

H.E.S.S. observations of the Crab during its March 2013 GeV gamma-ray flare

Abramowski¹,

Aharonian²,

Benkhali³

et al. 2014

A&A

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Context. On March 4, 2013 the Fermi-LAT and AGILE reported a flare from the direction of the Crab nebula in which the high-energy (HE; E > 100 MeV) flux was six times above its quiescent level. Simultaneous observations in other energy bands give us hints about the emission processes during the flare episode and the physics of pulsar wind nebulae in general. Aims. We search for variability in the emission of the Crab nebula at very-high energies (VHE; E > 100 GeV), using contemporaneous data taken with the H.E.S.S. array of Cherenkov telescopes. Methods. Observational data taken with the H.E.S.S. instrument on five consecutive days during the flare were analysed for the flux and spectral shape of the emission from the Crab nebula. Night-wise light curves are presented with energy thresholds of 1 TeV and 5 TeV.Results. The observations conducted with H.E.S.S. on March 6 to March 10, 2013 show no significant changes in the flux. They limit the variation in the integral flux above 1 TeV to less than 63% and the integral flux above 5 TeV to less than 78% at a 95% confidence level.

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Section: Discussionmentioning

confidence: 99%

H.E.S.S. observations of the Crab during its March 2013 GeV gamma-ray flare

Abramowski¹,

Aharonian²,

Benkhali³

et al. 2014

A&A

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“…Kaspi et al 2007), providing ideal conditions for inverse Compton scattering with relativistic electrons from the jet (e.g. Arshakian et al 2012;Dermer et al 1997). In addition, the observed variability timescales place constraints on the size of the emitting region owing to causality arguments.…”

Section: Discussionmentioning

confidence: 99%

Relativistic outflow drivesγ-ray emission in 3C 345

Schinzel

Lobanov

Taylor

et al. 2012

A&A

100

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Aims. On the basis of the first 20 months of Fermi-LAT data and optical monitoring, the quasar 3C 345 has been identified as a γ-ray emitter. We investigate whether there is a connection between the γ-ray and optical variability of 3C 345 and the properties of its parsec-scale radio emission. Methods. We combined the Fermi-LAT data of 3C 345, covering an energy range of 0.1-300 GeV, with 32 Very Long Baseline Array observations of the object made at 43.2 GHz in the period of January 2008-March 2010.Results. The VLBA data reveal the morphology and kinematics of the flow on scales of up to ≈5 milliarcseconds (deprojected linear distances of 380 parsecs). The brightness temperature, T b (r), measured along the jet first decreases with distance ∝r −(0.95 ± 0.69) and later exhibits a break at ≈0.3 milliarcseconds (mas), with T b (r) ∝ r −(4.11 ± 0.85) at larger separations. Variations in the γ-ray, optical, and parsec-scale radio emission display a similar long-term trend that persists during the entire VLBA monitoring period. The γ-ray and optical variations on shorter timescales are related to structural changes in the jet on scales of ≈0.3 mas (≈23 parsecs, deprojected), with the γ-ray and optical flares possibly being related to the evolution of four distinct superluminal components identified in the flow. Conclusions. The observations indicate that both the quiescent and flaring components of the γ-ray emission are produced in a region of the jet that extends up to ∼23 pc. This region may correspond to the Compton-loss dominated zone of the flow and its large extent may favor the synchrotron self-Compton mechanism for γ-ray production in the relativistic jet of the quasar 3C 345.

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“…For low-frequency-peaked BL Lacs (LBLs) and flatspectrum radio quasars (FSRQs), it is generally accepted that leptonic models require external photon sources for Compton scattering (EC = External Compton) to produce the γ-ray emission (e.g., Dermer et al 1997;Sambruna et al 1997;Mukherjee et al 1999;Madejski et al 1999;Böttcher & Bloom 2000;Hartman et al 2001). In the case of quasars, the most prominent external radiation field might be the quasi-isotropic radiation field of the broad-line region (BLR), as long as the emission region is located within the BLR.…”

Section: Interpretation and Model Implicationsmentioning

confidence: 99%

Radio-optical-gamma-ray properties of MOJAVE AGN detected byFermi/LAT

Arshakian¹,

Böttcher²,

Torrealba³

et al. 2011

A&A

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Aims. We use a sample of 83 core-dominated active galactic nuclei (AGN) selected from the MOJAVE (Monitoring of Jets in AGN with VLBA Experiments) radio-flux-limited sample and detected with the Fermi Large Area Telescope (LAT) to study the relations between non-simultaneous radio, optical, and γ-ray measurements. Methods. We perform a multi-band statistical analysis to investigate the relations between the emissions in different bands and reproduce these relations by modeling of the spectral energy distributions of blazars.Results. There is a significant correlation between the γ-ray luminosity and the optical nuclear and radio (15 GHz) luminosities of blazars. We report a well defined positive correlation between the γ-ray luminosity and the radio-optical loudness for quasars and BL Lacertae type objects (BL Lacs). A strong positive correlation is found between the radio luminosity and the γ-ray-optical loudness for quasars, while a negative correlation between the optical luminosity and the γ-ray-radio loudness is present for BL Lacs. Modeling of these correlations with a simple leptonic jet model for blazars indicates that variations of the accretion disk luminosity (and hence the jet power) is able to reproduce the trends observed in most of the correlations. To reproduce all observed correlations, variations of several parameters, such as the accretion power, jet viewing angle, Lorentz factor, and magnetic field of the jet, are required.

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Nonthermal Compton and Synchrotron Processes in the Jets of Active Galactic Nuclei

Cited by 164 publications

References 30 publications

H.E.S.S. observations of the Crab during its March 2013 GeV gamma-ray flare

H.E.S.S. observations of the Crab during its March 2013 GeV gamma-ray flare

Relativistic outflow drivesγ-ray emission in 3C 345

Radio-optical-gamma-ray properties of MOJAVE AGN detected byFermi/LAT

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