Optical Quasi-periodic Oscillation of the BL Lacertae Object S5 0716+714 during the Faint State

Hong, Su Young; Xiong, Dingrong; Bai, J. M.

doi:10.3847/1538-3881/aa9d89

Cited by 31 publications

(32 citation statements)

References 52 publications

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“…We can model such a PSD using a constant in the frequency domain. With N different PSD frequencies, the probability (p) that the maximum power at any frequency crossing a threshold (z) is given by p(>z) ≈ N e −z (Scargle 1982;Hong et al 2018), quantifying the false alarm probability (FAP), or the significance of the peak. The lower the FAP of a period peak, the less likely it is to be caused by statistical fluctuation.…”

Section: Significance Estimationmentioning

confidence: 99%

Multi-waveband quasi-periodic oscillations in the light curves of blazar CTA 102 during its 2016–2017 optical outburst

Sarkar

Kushwaha

Gupta

et al. 2020

A&A

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Context. Quasi-periodic fluctuations in the light curves of blazars can provide insight into the underlying emission process. This type of flux modulation hints at periodic physical processes that result in emission. CTA 102, a flat spectrum radio quasar at a redshift of 1.032, has displayed significant activity since 2016. The multi-waveband light curve of CTA 102 shows signs of quasi-periodic oscillations during the 2016–2017 flare. Aims. Our goal is to rigorously quantify the presence of any possible periodicity in the emitted flux during the mentioned period and to explore the possible causes that can give rise to it. Methods. Techniques such as the Lomb-Scargle periodogram and weighted wavelet z-transform were employed to observe the power emitted at different frequencies. To quantify the significance of the dominant period, Monte-Carlo techniques were employed to consider an underlying smooth bending power-law model for the power spectrum. In addition, the light curve was modeled using an autoregressive process (AR1) to analytically obtain the significance of the dominant period. Lastly, the light curve was modeled using a generalized autoregressive integrated moving average (ARIMA) process to check whether introducing a seasonal (periodic) component results in a statistically preferable model. Results. Highly significant, simultaneous quasi-periodic oscillations (QPOs) were observed in the γ-ray and optical fluxes of blazar CTA 102 during its highest optical activity episode in 2016–2017. The periodic flux modulation had a dominant period of ∼7.6 days and lasted for ∼8 cycles (MJD 57710–57770). All of the methods used point toward significant (> 4σ) quasi-periodic modulation in both γ-ray and optical fluxes. Conclusions. Several possible models were explored while probing the origin of the periodicity, and by extension, the 2016–2017 optical flare. The best explanation for the detected QPO appears to be a region of enhanced emission (blob), moving helically inside the jet.

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Section: Significance Estimationmentioning

confidence: 99%

Multi-waveband quasi-periodic oscillations in the light curves of blazar CTA 102 during its 2016–2017 optical outburst

Sarkar

Kushwaha

Gupta

et al. 2020

A&A

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show abstract

“…Although some observers remain skeptical about the existence of micro-variability, many observations and analytical methods have been established for the micro-variability of AGN (Meng et al 2017;Carini et al 1992;Villata et al 2002;Gaur et al 2015;Hagen-Thorn et al 2002;Pollock et al 2007). Gupta et al (2009) and Hong et al (2018) reported the optical quasi-period oscillation for S5 0716+714, which were explained by accretion disk fluctuations or oscillations. Very long baseline interferometry (VLBI) observations of the blazar jets in the form of radio knots proved the existence of postulated compact regions, and the apparent super-luminal motion (Bartel et al 1986).…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Microvariability Properties of the Blazar S5 0716+714

Webb

et al. 2019

ApJ

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The typical blazar S5 0716+714 is very interesting due to its rapid and large amplitude variability and high duty cycle of micro-variability in optical band. We analyze the observations in I, R and V bands obtained with the 1.0m telescope at Weihai observatory of Shandong University from 2011 to 2018. The model of synchrotron radiation from turbulent cells in a jet has been proposed as a mechanism for explaining micro-variability seen in blazar light curves. Parameters such as the sizes of turbulent cells, the enhanced particle densities, and the location of the turbulent cells in the jet can be studied using this model. The model predicts a time lag between variations as observed in different frequency bands. Automatic model fitting method for micro-variability is developed, and the fitting results of our multi-frequency micro-variability observations support the model. The results show that both the amplitude and duration of flares decomposed from the micro-variability light curves confirm to the log-normal distribution. The turbulent cell size is within the range of about 5 to 55 AU, and the time lags of the micro-variability flares between the I-R and R-V bands should be several minutes. The time lags obtained from the turbulence model are consistent with the fitting statistical results, and the time lags of flares are correlated with the time lags of the whole light curve.

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“…Red-noise spectra are characteristic of auto-regressive (AR) processes where activity at an instant is related to past activities (e.g. Schulz & Mudelsee 2002;Fan et al 2014;Zhang et al 2018;Xiong et al 2017;Hong et al 2018;Gupta, et al 2018). AGN emissions are generally autoregressive and usually can be convincingly modeled using an AR1 process where the present emission depends on the emission that immediately precedes it, i.e.,…”

Section: Redfit Analysismentioning

confidence: 99%

A Possible $γ$-ray Quasi-periodic Oscillation of $\sim$ 314 days in the Blazar OJ 287

Kushwaha,

Sarkar,

Gupta

et al. 2020

Preprint

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We report the detection of a probable γ-ray quasi-periodic oscillation (QPO) of around 314 days in the monthly binned 0.1 -300 GeV γ-ray Fermi-LAT light curve of the well known BL Lac blazar OJ 287. To identify and quantify the QPO nature of the γ-ray light curve of OJ 287, we used the Lomb-Scargle periodogram (LSP), REDFIT, and weighted wavelet z-transform (WWZ) analyses. We briefly discuss possible emission models for radio-loud active galactic nuclei (AGN) that can explain a γ-ray QPO of such a period in a blazar. Reports of changes in the position of quasi-stationary radio knots over a yearly timescale as well as a strong correlation between gamma-ray and mm-radio emission in previous studies indicate that the signal is probably associated with these knots.

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Optical Quasi-periodic Oscillation of the BL Lacertae Object S5 0716+714 during the Faint State

Cited by 31 publications

References 52 publications

Multi-waveband quasi-periodic oscillations in the light curves of blazar CTA 102 during its 2016–2017 optical outburst

Multi-waveband quasi-periodic oscillations in the light curves of blazar CTA 102 during its 2016–2017 optical outburst

Statistical Analysis of Microvariability Properties of the Blazar S5 0716+714

A Possible $γ$-ray Quasi-periodic Oscillation of $\sim$ 314 days in the Blazar OJ 287

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