The intraday variability in the radio-selected and 
 X-ray-selected BL Lacertae objects

Bai, J. M.; Xie, Gaogang; Li, K. H.; Zhang, X.; Liu, W. W.

doi:10.1051/aas:1998360

Cited by 60 publications

(10 citation statements)

References 25 publications

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“…In a study of several BL Lac objects consisting of the radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs), Bai et al [11] found that XBLs show more frequent microvariability than RBLs. Kraus et al [12] observed that intraday variations are common in RL AGNs and that the flux variations are often accompanied by similar variations in the linear polarization.…”

Section: Introductionmentioning

confidence: 99%

Microvariability in BL Lacertae: “Zooming” into the Innermost Blazar Regions

Bhatta

Webb

2018

Galaxies

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In this work, we present the results of our multi-band microvariability study of the famous blazar BL Lac. We performed microvariablity observations of the source in the optical VRI bands for four nights in 2016. We studied the intranight flux and spectral variability of the source in detail with an objective to characterize microvariability in the blazars, a frequently observed phenomenon in blazars. The results show that the source often displays a fast flux variability with an amplitude as large as ~0.2 magnitude within a few hours, and that the color variability in the similar time scales can be characterized as “bluer-when-brighter” trend. We also observed markedly curved optical spectrum during one of the nights. Furthermore, the correlation between multi-band emission shows that in general the emission in all the bands are highly correlated; and in one of the nights V band emission was found to lead the I band emission by ~13 min. The search for characteristic timescale using z-transformed auto-correlation function and the structure function analyses reveals characteristic timescale of ~50 min in one of the R band observations. We try to explain the observed results in the context of the passage of shock waves through the relativistic outflows in blazars.

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Section: Introductionmentioning

confidence: 99%

Microvariability in BL Lacertae: “Zooming” into the Innermost Blazar Regions

Bhatta

Webb

2018

Galaxies

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“…The periodic variabilities of blazars have been investigated extensively in the optical band (e.g., Bai et al 1998Bai et al , 1999Fan & Lin 2000;Xie et al 2008;Li et al 2009;Urry 2011;King et al 2013;Zhang et al 2014;Bhatta et al 2016;Fan et al 2016). An interesting case is that of OJ 287, which has a ∼12 yr period cycle (Kidger et al 1992;Valtonen et al 2006).…”

Section: Introductionmentioning

confidence: 99%

A γ-ray Quasi-periodic Modulation in the Blazar PKS 0301–243?

Zhang

Yan

Zhou

et al. 2017

ApJ

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We report a nominally high-confidence γ-ray quasi-periodic modulation in the blazar PKS 0301-243. For this target, we analyze its Fermi-LAT Pass 8 data from 2008 August to 2017 May. Two techniques, i.e., maximum likelihood optimization and exposure-weighted aperture photometry, are used to build the γ-ray light curves. Then, both the Lomb-Scargle periodogram and the weighted wavelet Z-transform are applied to the light curves to search for period signals. A quasi-periodicity with a period of 2.1±0.3 yr appears at the significance level of s5 , although it should be noted that this putative quasi-period variability is seen in a data set that is barely four times longer. We speculate that this γ-ray quasi-periodic modulation may be evidence of a binary supermassive black hole.

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“…In the last two decades, variability of blazars in radio to optical bands on diverse time scales has been reported in a large number of papers (e.g. Miller et al 1989;Courvoisier et al 1995;Heidt & Wagner 1996;Takalo et al 1996;Sillanpää et al 1996aSillanpää et al , 1996bBai et al 1998Bai et al , 1999Fan et al 1998Fan et al , 2002Fan et al , 2007Xie et al 2002a;Gupta et al 2004;Ciprini et al 2003, 2007 andreferences therein).…”

Section: Introductionmentioning

confidence: 99%

Optical Intra-Day Variability in Blazars

Gupta

Jiang

Bai

et al. 2008

The Astronomical Journal

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120

152

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We selected a sample of a dozen blazars which are the prime candidates for simultaneous multi-wavelength observing campaigns in their outburst phase. We searched for optical outbursts, intra-day variability (IDV) and short-term variability in these blazars. We carried out optical photometric monitoring of nine of these blazars in 13 observing nights during our observing run of 2006 October 27-2007 March 20 using the 1.02 m optical telescope equipped with CCD detector and BVRI Johnson broadband filters at Yunnan Astronomical Observatory, Kunming, China. From our observations, our data favor the hypothesis that three blazars, AO 0235+164, S5 0716+714, and 3C 279, were in the outburst state; one blazar, 3C 454.3, was in the post-outburst state; three blazars, S2 0109+224, PKS 0735+178, and OJ 287, were in the pre/post-outburst state; one blazar, ON 231, was in the low state; and the state of one blazar, 1ES 2344+514, was not known because there are not many optical data available for the blazar to compare with our observations. We observed densely sampled 1534 image frames of these nine blazars. Out of three nights of observations of AO 0235+164, IDV was detected in two nights. Out of five nights of observations of S5 0716+714, IDV was detected in two nights. In one night of observations of PKS 0735+178, IDV was detected. Out of six nights of observations of 3C 454.3, IDV was detected in three nights. No IDV was detected in S2 0109+224, OJ 287, ON 231, 3C 279, and 1ES 2344+514 in their one, four, one, two, and one nights of observations, respectively. AO 0235+164, S5 0716+714, OJ 287, 3C 279, and 3C 454.3 were observed in more than one night and short-term variations in all these blazars were also noticed. From our observations and the available data, we found that the predicted optical outbursts with time intervals of ∼8 years in AO 0235+164 and ∼3 years in S5 0716+714 have possibly occurred.

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The intraday variability in the radio-selected and X-ray-selected BL Lacertae objects

Cited by 60 publications

References 25 publications

Microvariability in BL Lacertae: “Zooming” into the Innermost Blazar Regions

Microvariability in BL Lacertae: “Zooming” into the Innermost Blazar Regions

A γ-ray Quasi-periodic Modulation in the Blazar PKS 0301–243?

Optical Intra-Day Variability in Blazars

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