Seven-Year Multi-Color Optical Monitoring of Bl Lacertae Object S5 0716+714

Dai, Yan; Wu, Jinfeng; Zhu, Zong-Hong; Zhou, Xu; Ma, Jun; Yuan, Qirong; Wang, Lingzhi

doi:10.1088/0067-0049/204/2/22

Cited by 26 publications

(34 citation statements)

References 33 publications

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“…On JD 2456965, an extremely violent light curve was captured. The changing rate of magnitude in the B band reaches 0.347 mags·h −1 , which is close to the highest record in the R band of 0.38 mags·h −1 [9] and exceeds Dai et al's [10] 0.106 mags·h −1 and Nesci et al's [11] 0.16 mags·h −1 . Besides, the light curve on that day shows a double-peak shape overlapped by three sub-flares, and quasi-periodic oscillations (QPO) was detected.…”

Section: Light Curvessupporting

confidence: 66%

Intra-Day Simultaneous Optical Monitoring of S5 0716+714

Zhang

Man

2016

Galaxies

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Abstract:We present the results of simultaneous optical multi-color observations of BL Lac object 0716+714 in November 2014 and February 2016. The intra-day variability (IDV) varies from 0.04 to 0.3 mags. Both achromatic and bluer-when-brighter (BWB) color behaviors were detected. A probable quasi-periodic oscillation overlapping on a significant flare was also observed. We used the interpolated cross-correlation function to calculate time lags between light curves in different bands. Variations in the B and R lagging behind that in the I band were found, which corresponds with anti-clockwise loops on the color-magnitude diagrams.

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Section: Light Curvessupporting

confidence: 66%

Intra-Day Simultaneous Optical Monitoring of S5 0716+714

Zhang

Man

2016

Galaxies

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“…We note that this source is known for its persistent variability down to the timescales of hours and minutes, both in total and in polarized optical fluxes (Sasada et al 2008;Dai et al 2013;Bhatta et al 2013).…”

Section: Introductionmentioning

confidence: 88%

Longterm optical monitoring of bright BL Lacertae objects with ATOM: Spectral variability and multiwavelength correlations

Wierzcholska

Ostrowski

Stawarz

et al. 2014

A&A

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Context. Blazars are the established sources of an intense and variable non-thermal radiation extending from radio wavelengths up to high and very high-energy γ-rays. Understanding the spectral evolution of blazars in selected frequency ranges, as well as multifrequency correlations in various types of blazar sources, is of a primary importance for constraining blazar physics. Aims. We present the results of a long-term optical monitoring of a sample of 30 blazars of the BL Lac type, most of which are the confirmed TeV emitters. We study the optical color-magnitude correlation patterns emerging in the analyzed sample and compare the optical properties of the targets with the high-energy γ-ray and high-frequency radio data. Methods. The optical observations were carried out in R and B filters using the Automatic Telescope for Optical Monitoring (ATOM) located at the site of the H.E.S.S. Array. Each object in the sample was observed during at least 20 nights in the period 2007 to 2012. Results. We find significant overall color-magnitude correlations (meaning bluer-when-brighter spectral evolution) in 40% of the sample. The sources that do not display any clear chromatism in the full datasets often do exhibit bluer-when-brighter behavior but only in isolated shorter time intervals. We also discovered spectral state transitions at optical wavelengths in several of the analyzed sources. Finally, we find that the radio, optical, and γ-ray luminosities of the sources in the sample obey almost linear correlations, which seem induced, at least partly, by the redshift dependence and may also be affected by the non-simultaneity of the analyzed multifrequency dataset. Conclusions. We argue that the observed bluer-when-brighter behavior is intrinsic to the jet-emission regions, at least for some of these blazars, rather than resulting from the contamination of the measured flux by the starlight of host galaxies. We also conclude that the significance of color-magnitude scalings does not correlate with the optical color, but instead seems to depend on the source luminosity, in that these are the lowest luminosity BL Lac objects to display the strongest correlations.

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“…Similar findings were made by [33], where they found that their sample of BL Lacs showed complicated color-magnitude diagram behavior including hysteresis tracks, as well as achromatic flares; these indicate that different jet components dominate at different times. Dai [44] found intra-day spectral hysteresis loop patterns for the blazar S5 0716 + 714 in its color-magnitude diagram. These loop-like patterns are attributed to the differences in the amplitudes and cadences at different wavelengths [18].…”

Section: Color Indicesmentioning

confidence: 99%

Multi-Band Intra-Night Optical Variability of BL Lacertae

et al. 2017

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Abstract:We monitored BL Lacertae frequently during 2014-2016 when it was generally in a high state. We searched for intra-day variability for 43 nights using quasi-simultaneous measurements in the B, V, R, and I bands (totaling 143 light curves); the typical sampling interval was about eight minutes. On hour-like timescales, BL Lac exhibited significant variations during 13 nights in various optical bands. Significant spectral variations are seen during most of these nights such that the optical spectrum becomes bluer when brighter. The amplitude of variability is usually greater for longer observations but is lower when BL Lac is brighter. No evidence for periodicities or characteristic variability time-scales in the light curves was found. The color variations are mildly chromatic on long timescales.

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Seven-Year Multi-Color Optical Monitoring of Bl Lacertae Object S5 0716+714

Cited by 26 publications

References 33 publications

Intra-Day Simultaneous Optical Monitoring of S5 0716+714

Intra-Day Simultaneous Optical Monitoring of S5 0716+714

Longterm optical monitoring of bright BL Lacertae objects with ATOM: Spectral variability and multiwavelength correlations

Multi-Band Intra-Night Optical Variability of BL Lacertae

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