Possible Accretion Disk Origin of the Emission Variability of a Blazar Jet

Chatterjee, Ritaban; Roychowdhury, Agniva; Chandra, Sunil; Sinha, Atreyee

doi:10.3847/2041-8213/aac48a

Cited by 36 publications

(36 citation statements)

References 52 publications

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“…The variability thus is indicative of essentially "pink/flicker noise" type at these higher frequencies of the electromagnetic spectrum. We note that the PSD slopes derived here for the Xray light curves are in good agreement with β ∼1.2-1.5 reported in Isobe et al (2015); Chatterjee et al (2018) for the blazar Mrk 421. Similarly, the PSD slopes derived at VHE and HE γ−ray light curves by means of the DFT method, are in good agreement with β ∼1.2 and ∼1.1 reported in (Table 1).…”

Section: Resultssupporting

confidence: 90%

Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155−304

Goyal

2020

Monthly Notices of the Royal Astronomical Society

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We present the results of the power spectral density (PSD) analysis for the blazars Mrk 421 and PKS 2155−304, using good-quality, densely sampled light curves at multiple frequencies, covering 17 decades of the electromagnetic spectrum, and variability timescales from weeks up to a decade. The data were collected from publicly available archives of observatories at radio from OVRO, optical and infrared (B, V, R, I, J, H, and K-bands), X-rays from the Swift and the Rossi X-ray Timing Explorer, high and very high energy γ−rays from the Fermi and Very Energetic Radiation Imaging Telescope Array System as well as the High Energy Stereoscopic System. Our results are: (1) the power-law form of the variability power spectra at radio, infra-red and optical frequencies have slopes ∼1.8, indicative of random-walk type noise processes;(2) the power-law form of the variability power spectra at higher frequencies, from Xrays to very high energy γ-rays, however, have slopes ∼1.2, suggesting a flicker noise type process; (3) there is significantly more variability power at X-rays, high and very high energy γ-rays on timescales 100 days, as compared to lower energies. Our results do not easily fit into a simple model, in which a single compact emission zone is dominating the radiative output of the blazars across all the timescales probed in our analysis. Instead, we argue that the frequency-dependent shape of the variability power spectra points out a more complex picture, with highly inhomogeneous outflow producing non-thermal emission over an extended, stratified volume.

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Section: Resultssupporting

confidence: 90%

Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155−304

Goyal

2020

Monthly Notices of the Royal Astronomical Society

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“…While such a break has not been found in the power spectra of the emission variability in many blazars it has been observed in a few cases. Most recently Chatterjee et al (2018) have confirmed the presence of a break in the X-ray power spectral density of the blazar Mrk 421, which was previously hinted by other authors (Kataoka et al 2001;Isobe et al 2015). Goyal et al (2018) have inferred a break time-scale in the γ-ray variability of another BL Lac object OJ 287 from their analysis of its Fermi-LAT light curve.…”

Section: Introductionsupporting

confidence: 55%

The accretion disc-jet connection in blazars

Mukherjee

Mitra

Chatterjee

2019

Monthly Notices of the Royal Astronomical Society

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The power spectral density (PSD) of the X-ray emission variability from the accretion disccorona region of black hole X-ray binaries and active galactic nuclei has a broken power-law shape with a characteristic break time-scale T B . If the disc and the jet are connected, the jet variability may also contain a characteristic time-scale related to that of the disc-corona. Recent observations of the blazar Mrk 421 have confirmed the broken power-law shape of the PSD of its jet X-ray variability. We model the time variability of a blazar, in which emitting particles are assumed to be accelerated by successive shock waves flowing down the jet with a varying inter-shock time-scale (T I S ). We investigate the possible relation between the characteristic time-scales in the disc and jet variability based on the above model, along with mathematically and physically simulated disc variability. We find that both the PSD of the jet and disc variability may have a broken power-law shape but the break time-scales are not related in general except only in systems with a small range of BH mass. The break in the jet and the disc PSD are connected to the interval between large amplitude outbursts in the jet (T I S ) and to the viscous time-scale in the disc, respectively. In frequency bands where multiple emission processes are involved or emission is from lower energy particles, the break in the PSD may not be prominent enough for detection.

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“…Alternatively, similar PSDs at different wavelengths might only imply a common origin of the variability, as would be the case in the inner propagating fluctuations model. PSD breaks on the order of days have been detected in several of our sources in the X-ray (Kataoka et al 2001(Kataoka et al , 2002McHardy 2008;Chatterjee et al 2018) and the extreme ultraviolet (Cagnoni et al 2001). The γray PSDs are all close to the measurement noise level at these timescales, however, so detection of similar breaks was not possible.…”

Section: Origin Of Variability Timescalesmentioning

confidence: 80%

Characteristic Variability Timescales in the Gamma-Ray Power Spectra of Blazars

Ryan

Siemiginowska

Sobolewska

et al. 2019

ApJ

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Characteristic variability timescales in blazar γ-ray light curves can provide insight into the physical processes responsible for the γ-ray variability. The power spectral density (PSD) is capable of revealing such timescales, which may appear as breaks or periodicities. Continuous-time autoregressive movingaverage (CARMA) models can be used to accurately estimate a light curve's PSD. Through a lightcurve simulation study, we develop a methodology to identify PSD breaks using CARMA models. Using this methodology, we study the γ-ray light curves of 13 bright blazars observed with the Fermi Large Area Telescope in the 0.1-300 GeV band over 9.5 years. We present the blazar γ-ray PSDs, which provide evidence for low-frequency breaks on timescales ∼1 year in four sources, and an additional high-frequency break on a timescale ∼9 days in one source.

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Possible Accretion Disk Origin of the Emission Variability of a Blazar Jet

Cited by 36 publications

References 52 publications

Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155−304

Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155−304

The accretion disc-jet connection in blazars

Characteristic Variability Timescales in the Gamma-Ray Power Spectra of Blazars

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