Spectral Variability of the Blazar 3C 279 in the Optical to X-Ray Band during 2009–2018

Yoo, Sungmin; An, Hongjun

doi:10.3847/1538-4357/abb3c1

Cited by 7 publications

(6 citation statements)

References 34 publications

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“…The time delays between the X-ray and the optical are t = --+ 8 days. Yoo & An (2020) has reported that the X-ray leads the optical for about 60 days, which agrees with our result within errors.…”

Section: Time Lag Analysissupporting

confidence: 93%

“…In recent years, the collection of multiple-wavelength data for a decade long duration enables the comprehensive investigation of multi-wavelength activity at different periods (Isler et al 2017;Patiño-Álvarez et al 2018;Rani et al 2018;Agarwal et al 2019;Larionov et al 2020;Yoo & An 2020). Isler et al (2017) investigated the seven-year optical/infrared (OIR) color index variations.…”

Section: Introductionmentioning

confidence: 99%

“…They found an anticorrelation between the γ-ray luminosity and γray spectral index, and presented that the location of γ-ray emitting region changes in different activity states. Yoo & An (2020) analyzed the correlation between fluxes and spectral indices at different bands for three states, and found a time lag of 65 days between optical and X-ray in one state. The polarization behavior could also help us to understand the radiation and variation mechanism deeply.…”

Section: Introductionmentioning

confidence: 99%

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Multiple-wavelength Correlation and Variation Study for 3C 279 at Various Timescales

Chen,

Jiang

2023

PASP

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The study on variation phenomena of blazars can shed light on the jet activity and structures. We collect nearly ten years γ-ray, X-ray, optical, and radio light curves of the target 3C 279, and use the local cross-correlation function to perform the correlation analysis among them. Based on lags among different wavelengths, we obtain that the optical as well as the X-ray emitting regions are 32.5 − 0.9 + 2.9 and 8.4 − 4.4 + 7.7 pc away from the jet base, and are upstream of the radio core region. The optical and γ-ray emitting regions are not completely co-spatial. We select several periods to study various variation phenomena at long-term, short-term, and very-short-term timescales. We find a redder when brighter trend of the optical color index at the quiescent state and a bluer when brighter trend at the active state. We also find a softer when brighter trend of the γ-ray at low luminosity and a possible harder when brighter trend at high luminosity. The correlation between the optical polarization and fluxes is complex. We find an anticorrelation for one long-term flare, and positive correlations for two short-term flares. The stack of the multiple optical components can explain the anticorrelation, while the appearance of a dominating component can explain the positive correlations. The disk plus many jet components scenario can explain the complex optical variation behaviors for 3C 279. As a remarkable intermediate synchrotron peaked blazar target, 3C 279 play an important role to understand the classification and transition between the low synchrotron peaked and high synchrotron peaked subclass of blazars, since its variation phenomena shows the indication of connection between these two categories.

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Section: Time Lag Analysissupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiple-wavelength Correlation and Variation Study for 3C 279 at Various Timescales

Chen,

Jiang

2023

PASP

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“…Studying systems that alternate between FSRQ and BL Lac states, using photometric and spectroscopic data, should illuminate their differences, but there are few studies in literature that can really be used to explore the question of blazar unification. While there are many studies of blazar variability at particular energies as well as studies of correlations of the variability between different energies and changes in the overall SED (Paliya 2015;Zhang et al 2015;Yoo & An 2020), there are many fewer spectroscopic monitoring studies of blazars (e.g., Zheng & Burbidge 1986;Bregman et al 1986;Perez et al 1989;Vermeulen et al 1995;Ulrich et al 1997;Corbett et al 2000). In a few cases, large emission line flux changes have been observed.…”

Section: Introductionmentioning

confidence: 99%

The Changing-look Blazar B2 1420+32

Mishra

Dai

Chen

et al. 2021

ApJ

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Blazars are active galactic nuclei with their relativistic jets pointing toward the observer, comprising two major subclasses, flat-spectrum radio quasars (FSRQs) and BL Lac objects. We present multiwavelength photometric and spectroscopic monitoring observations of the blazar B2 1420+32, focusing on its outbursts in 2018–2020. Multiepoch spectra show that the blazar exhibited large-scale spectral variability in both its continuum and line emission, accompanied by dramatic gamma-ray and optical variability by factors of up to 40 and 15, respectively, on week to month timescales. Over the last decade, the gamma-ray and optical fluxes increased by factors of 1500 and 100, respectively. B2 1420+32 was an FSRQ with broad emission lines in 1995. Following a series of flares starting in 2018, it transitioned between BL Lac and FSRQ states multiple times, with the emergence of a strong Fe pseudocontinuum. Two spectra also contain components that can be modeled as single-temperature blackbodies of 12,000 and 5200 K. Such a collection of “changing-look” features has never been observed previously in a blazar. We measure gamma-ray–optical and interband optical lags implying emission-region separations of less than 800 and 130 gravitational radii, respectively. Since most emission-line flux variations, except the Fe continuum, are within a factor of 2–3, the transitions between FSRQ and BL Lac classifications are mainly caused by the continuum variability. The large Fe continuum flux increase suggests the occurrence of dust sublimation releasing more Fe ions in the central engine and an energy transfer from the relativistic jet to subrelativistic emission components.

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“…SED MODELING Multiwavelength SED modeling can shed light on the mechanisms of gamma-ray production during VHE flares. For 3C 279, we refer the reader to those works in the literature in which multiwavelength SED modeling of the epochs considered here has been performed, and we do not perform any additional modeling (see for example, Hayashida et al 2015;Ackermann et al 2016;Prince 2020;Yoo & An 2020).…”

Section: Daily and Sub-daily Variabilitymentioning

confidence: 99%

Variability and Spectral Characteristics of Three Flaring Gamma-ray Quasars Observed by VERITAS and Fermi-LAT

Adams,

Batshoun,

Benbow

et al. 2021

Preprint

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Flat spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies, but only rarely emit detectable fluxes of TeV gamma rays, typically during bright GeV flares. We explore the gamma-ray variability and spectral characteristics of three FSRQs that have been observed at GeV and TeV energies by Fermi -LAT and VERITAS, making use of almost 100 hours of VERITAS observations spread over 10 years: 3C 279, PKS 1222+216, and Ton 599. We explain the GeV flux distributions of the sources in terms of a model derived from a stochastic differential equation describing fluctuations in the magnetic field in the accretion disk, and estimate the timescales of magnetic flux accumulation and stochastic instabilities in their accretion disks. We identify distinct flares using a procedure based on Bayesian blocks and analyze their daily and sub-daily variability and gamma-ray energy spectra. Using observations from VERITAS as well as Fermi, Swift, and the Steward Observatory, we model the broadband spectral energy distributions of PKS 1222+216 and Ton 599 during VHE-detected flares in 2014 and 2017, respectively, strongly constraining the jet Doppler factors and gamma-ray emission region locations during these events. Finally, we place theoretical constraints on the potential production of PeV-scale neutrinos during these VHE flares.

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Spectral Variability of the Blazar 3C 279 in the Optical to X-Ray Band during 2009–2018

Cited by 7 publications

References 34 publications

Multiple-wavelength Correlation and Variation Study for 3C 279 at Various Timescales

Multiple-wavelength Correlation and Variation Study for 3C 279 at Various Timescales

The Changing-look Blazar B2 1420+32

Variability and Spectral Characteristics of Three Flaring Gamma-ray Quasars Observed by VERITAS and Fermi-LAT

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