Evidence for Two Lognormal States in Multi-Wavelength Flux Variation of FSRQ PKS 1510-089

Kushwaha, Pankaj; Chandra, Sunil; Misra, Ranjeev; Sahayanathan, S.; Singh, K. P.; Baliyan, K. S.

doi:10.3847/2041-8205/822/1/l13

Cited by 49 publications

(63 citation statements)

References 45 publications

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“…All the sources are detected over 97% (e.g. PKS 1510-089; Kushwaha et al 2016) of the total duration, thereby presenting one of the best sampled γ-ray light curves till date (on the timescale of days). The light curves clearly show different levels of variability for each source, an aspect of source and energy dependent variability.…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…On the other hand, a broader understanding of physical processes can be obtained by a careful and systematic investigation of the statistical properties in time domain of well selected sources over long timescales (e.g. Kushwaha et al 2016) by comparing with current blazars physics as well as with non-blazar counterparts and with other accretion-powered sources.…”

Section: Discussionmentioning

confidence: 99%

“…While the skewness deviates from zero for the three blazars, the deviation for the radio-galaxy is substantially less. We then thus checked the consistency of the distributions with a lognormal as is normally inferred for RQAGNs, GXBs and even blazars (Kushwaha et al 2016;H.E.S.S. Collaboration et al 2010;Giebels & Degrange 2009).…”

Section: Flux Distribution and Effect Of Photon Statisticsmentioning

confidence: 96%

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Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Kushwaha

Sinha

Misra

et al. 2017

ApJ

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We present a statistical characterization of the γ-ray emission from the four Fermi -LAT sources: FR I radio galaxy NGC 1275, BL Lac Mrk 421, FSRQs B2 1520+31 and PKS 1510-089 detected almost continuously over a time integration of 3-days between August 2008 -October 2015. The observed flux variation is large, spanning 2 orders of magnitude between the extremes except for Mrk 421. We compute the flux distributions and compare with Gaussian and lognormal ones. We find that the 3 blazars have distribution consistent with a lognormal, suggesting that the variability is of a non-linear, multiplicative nature. This is further supported by the computation of the flux-rms relation, which is observed to be linear for the 3 blazars. However, for NGC 1275, the distribution does not seem to be represented either by a lognormal or a Gaussian, while its flux-rms relation is still found to be linear. We also compute the power spectra, which suggest the presence of a break, but are consistent with typical scale-free power-law shot noise. The results are broadly consistent with the statistical properties of the magnetic reconnection powered minijets-in-a-jet model. We discuss other possible scenarios and implications of these observations on jet processes and connections with the central engine.

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Section: Analysis and Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Flux Distribution and Effect Of Photon Statisticsmentioning

confidence: 96%

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Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Kushwaha

Sinha

Misra

et al. 2017

ApJ

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“…These observations reveal a complex multiwavelength behavior [4,5,6,7] with changing correlation patterns between different energy bands. This also explains the difficulties in modeling the SED, which has resulted in different interpretations, such as the requirement of at least two radiative emission components to reproduce the inverse Compton component [8] or two spatially distinct emission zones [9].…”

Section: Introductionmentioning

confidence: 99%

The exceptional VHE gamma-ray outburst of PKS 1510-089 in May 2016

Zacharias¹,

Sitarek²,

Prester³

et al. 2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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PKS 1510-089 (z=0.361) is one of only a handful of flat spectrum radio quasars that have been detected at very high energy (VHE, E > 100 GeV) gamma rays. It is a very active source across the entire electromagnetic spectrum. VHE observations in May 2016 with H.E.S.S. and MAGIC revealed an exceptionally strong flare, which lasted for less than two nights, and exhibited a peak flux of about 0.8 times the flux of the Crab Nebula above 200 GeV. The flare provides the first evidence of intranight variability at VHE in this source. While optical observations with ATOM reveal a counterpart at optical frequencies, Fermi-LAT observations reveal only low flux variability at high energy (HE, E > 100 MeV) gamma rays. Interestingly, the HE spectral index significantly hardens during the peak of the VHE flare, indicating a strong shift of the peak frequency of the high energy component. Given the expected strong absorption due to the broad-line region, the VHE emission region cannot be located deep within that region.

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“…This allowed a detailed spectral, temporal, polarization, and imaging characterization of blazars, as well as exploration of correlations between them, thereby greatly enhancing our understanding of these sources and physical conditions within the relativistic jets.Spectral and temporal studies, in particular, high energy (HE) emission mechanisms and search for (quasi) periodic modulation has been one of the focus of intensive research, in addition to characterization based on these. Temporal studies of flux variability have firmly established it to be stochastic with statistical properties [2,8,9] broadly similar to those exhibited by other-accretion powered sources [10]. Though a few cases of firm quasi-periodic signals have been observed, significance of most of the detected signal is still marginal [e.g.…”

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confidence: 99%

A Multi-Wavelength View of OJ 287 Activity in 2015–2017: Implications of Spectral Changes on Central-Engine Models and MeV-GeV Emission Mechanism

Kushwaha

2020

Galaxies

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A diverse range of observational results and peculiar properties across the domains of observation have made OJ 287 one of the best-explored BL Lac objects on the issues of relativistic jets and accretion physics as well as the strong theory of gravity. We here present a brief compilation of observational results from the literature and inferences/insights from the extensive studies but focus on the interpretation of its ∼ 12-yr quasi-periodic optical outbursts (QPOOs) and high energy emission mechanisms. The QPOOs in one model are attributed to the disk-impact related to dynamics of the binary SMBHs while alternative models attribute it to the geometrical effect related to the precession of a single jet or double jets. We discuss implications of the new spectral features reported during the 2015-2017 multi-wavelength high activity of the source -a break in the NIR-optical spectrum and hardening of the MeV-GeV emission accompanied by a shift in the location of its peak, in the context of the two. The reported NIR-optical break nicely fits the description of a standard accretion disk emission from an SMBH of mass ∼ 10 10 M while the time of its first appearance in end-May 2013 (MJD 56439) is in close coincidence with the time of impact predicted by the disk-impact binary SMBH model. This spectral and temporal coincidence with the model parameters of the disk-impact binary SMBH model provides independent evidence in favor of the model over the geometrical models which argue a total central-engine mass in the range of 10 7−9 M . On the other hand, the MeV-GeV spectral change is naturally reproduced by the inverse Compton scattering of photons from the broad-line region and is consistent with the detection of broad emission lines during the previous cycles of quasi-periodic outbursts. Combining this with previous SED studies suggests that in OJ 287, MeV-GeV emission results from external Comptonization. 2 of 21 minutes and even less to decades 1 [∼ 6-7 orders of magnitude; e.g. 2]. Their radio and optical emission is highly polarized and have been observed to vary often with the source flux, all the way from 0 to > 50%. Imaging in radio, infra-red (IR), optical, and X-ray, on the other hand, show an extremely well collimated jet extending up to Mpc scales [∼ 9-13 orders of magnitude; e.g. 3,4] with frequent sighting of superluminal features in high-resolution imaging of the core. Taken together with the observational and theoretical understanding of other astrophysical objects combined with their high and rarely repeating observational behavior indicates that they are the site of complex, multi-level, multi-scale physics and thus, are normally called extreme sources among non-catastrophic events.Though studies in different energy bands finally culminated into a unified scheme for radio-loud AGNs [5], it also revealed that AGNs need well-coordinated multi-wavelength (MW) observations to go beyond the limits associated with individual bands. The launch of the gamma-ray survey observatory Fermi-LAT (Large Area Telescope...

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Evidence for Two Lognormal States in Multi-Wavelength Flux Variation of FSRQ PKS 1510-089

Cited by 49 publications

References 45 publications

Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

The exceptional VHE gamma-ray outburst of PKS 1510-089 in May 2016

A Multi-Wavelength View of OJ 287 Activity in 2015–2017: Implications of Spectral Changes on Central-Engine Models and MeV-GeV Emission Mechanism

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