Models of Variability in Blazar Jets

Mastichiadis, A.; Kirk, J. G.

doi:10.1071/as01108

Cited by 70 publications

(53 citation statements)

References 30 publications

(31 reference statements)

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“…It may be due to the intrinsic processes related to jet emission mechanism. Luminosity increase due to injection of fresh electrons with the energy distribution harder than that of the previously cooled ones can also cause flattening of spectrum as the object brightens (Mastichiadis & Kirk 2002). According to the shock-in-jet model, as the shock propagating down the jet strikes a region of high electron population, radiations at different visible colours is produced at different distances behind the shocks.…”

Section: Discussionmentioning

confidence: 99%

Multiband optical variability studies of BL Lacertae

Agarwal¹,

Gupta²

2015

Monthly Notices of the Royal Astronomical Society

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We monitored BL Lacertae for 13 nights in optical B, V, R, and I bands during October and November 2014 including quasi-simultaneous observations in V and R bands using two optical telescopes in India. We have studied multi-band optical flux variations, colour variation and spectral changes in this blazar. Source was found to be active during the whole monitoring period and showed significant intraday variability on 3 nights in V and R filters while displayed hints of variability on 6 other dates in R passband and on 2 nights in V filter. From the colour-magnitude analysis of the source we found that the spectra of the target gets flatter as it becomes brighter on intra-night timescale. Using discrete correlation technique, we found that intraday light curves in both V and R filters are almost consistent and well correlated with each other. We also generated spectral energy distribution (SED) of the target using the B, V, R, and I data sets for all 13 nights which could help us investigate the physical process responsible for the observed variations in BL Lacertae objects. We also discuss possible physical causes of the observed spectral variability.

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Section: Discussionmentioning

confidence: 99%

Multiband optical variability studies of BL Lacertae

Agarwal¹,

Gupta²

2015

Monthly Notices of the Royal Astronomical Society

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“…Mastichiadis & Kirk 2002;Kirk et al 1998). However, in blazars the nature of the correlation between the flux and the spectral index, so far, is somewhat uncertain.…”

Section: Achromatic Behaviormentioning

confidence: 99%

Radio and γ-Ray Variability in the BL Lac PKS 0219−164: Detection of Quasi-periodic Oscillations in the Radio Light Curve

Bhatta¹

2017

ApJ

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In this work, we explore the long-term variability properties of the blazar PKS 0219-164 in the radio and the γ-ray regime, utilizing the OVRO 15 GHz and the Fermi/LAT observations from the period 2008-2017. We found that γ-ray emission is more variable than the radio emission implying that γ ray emission possibly originated in more compact regions while the radio emission represented continuum emission from the large scale jets. Also, in γ-ray the source exhibited spectral variability characterized by the softer-when-brighter trend, a less frequently observed feature in the high energy emission by BL Lacs. In radio, using Lomb-Scargle periodogram and weighted wavelet z-transform, we detected a strong signal of quasi-periodic oscillation (QPO) with a periodicity of 270 ± 26 days with possible harmonics of 550 ± 42 and 1150 ± 157 days periods. At a time when detections of QPOs in blazars are still under debate, the observed QPO with high statistical significance ( ∼ 97% -99% global significance over underlying red-noise processes) and persistent over nearly 10 oscillations could make one of the strongest cases for the detection of QPOs in blazar light curves. We discuss various blazar models that might lead to the γ-ray and radio variability, QPO, and the achromatic behavior seen in the high energy emission from the source.

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“…The objective is to assess how the global character of the radio to X-ray to gammaray data can provide insights into the nature of the accelerator and its plasma environment. To facilitate this goal, we focus solely on leptonic models 6,7,8,20 , those with synchrotron emission predominantly at frequencies below 10…”

Section: Radiation Emission Modelingmentioning

confidence: 99%

“…This was almost contemporaneous with the determination that Mrk 421 also emitted at TeV energies 3 . The prevailing thought is that this gammaray signal is generated by inverse Compton scattering of either an IR/optical/UV photon source of possibly disk or ambient origin 4,5 , or of synchrotron photons by the same electrons that emit this radio-to-X-ray signal, so-called synchrotron-selfCompton (SSC) models 6,7,8 . An important recent development for blazar science has been the improvement of sensivity in the 100 MeV-100 GeV window, afforded by the Fermi-Large Area Telescope (LAT).…”

Section: Introductionmentioning

confidence: 99%

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Multiwavelength Probes of the Environs of Relativistic Shocks in Blazar Jets

Baring

Böttcher

Summerlin

2014

Int. J. Mod. Phys. Conf. Ser.

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Diffusive shock acceleration (DSA) at relativistic shocks is likely to be an important acceleration mechanism in various astrophysical jet sources, including radio-loud AGN. An important recent development for blazar science is the ability of Fermi-LAT data to pin down the power-law index of the high energy portion of emission in these sources, and therefore also the index of the underlying non-thermal particle population. This diagnostic potential was not possible prior to Fermi launch, when gamma-ray information was dominated by the highly-absorbed TeV band. This paper highlights how multiwavelength spectra including X-ray band and Fermi data can be used to probe diffusive acceleration in relativistic, oblique, MHD shocks in blazar jets. The spectral index of the non-thermal particle distributions resulting from Monte Carlo simulations of DSA, and the fraction of thermal particles accelerated to non-thermal energies, depend sensitively on the particles' mean free path scale, and also on the magnetic field obliquity to the shock normal. We investigate self-consistently the radiative synchrotron/Compton signatures of the resulting thermal and non-thermal particle distributions. Important constraints on the frequency of particle scattering and the level of field turbulence are identified for the blazar AO 0235+164. The possible interpretation that turbulence levels decline with remoteness from jet shocks, and a significant role for non-gyroresonant diffusion, are discussed.

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Models of Variability in Blazar Jets

Cited by 70 publications

References 30 publications

Multiband optical variability studies of BL Lacertae

Multiband optical variability studies of BL Lacertae

Radio and γ-Ray Variability in the BL Lac PKS 0219−164: Detection of Quasi-periodic Oscillations in the Radio Light Curve

Multiwavelength Probes of the Environs of Relativistic Shocks in Blazar Jets

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