Multi-color optical variability of the TeV blazar Mrk 501 in the low-state

Gupta, Alok C.; Deng, W.; Joshi, U.; Bai, J. M.; Lee, M.G.

doi:10.1016/j.newast.2007.12.001

Cited by 32 publications

(7 citation statements)

References 48 publications

(60 reference statements)

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“…Then we used SF, a powerful and well-studied method for period analysis (Simonetti et al 1985;Paltani et al 1997;Gupta et al 2008) seen that the results for B and V bands are in consistent with each other. Possible periods are presented in Col. 4 and Col. 5 of Tab.…”

Section: Periodicity Analysissupporting

confidence: 59%

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Long-term optical and radio variability of BL Lacertae

Guo

et al. 2015

New Astronomy

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Well-sampled optical and radio light curves of BL Lacertae in B, V, R, I bands and 4.8, 8.0, 14.5 GHz from 1968 to 2014 were presented in this paper. A possible $1.26 \pm 0.05$ yr period in optical bands and a $7.50 \pm 0.15$ yr period in radio bands were detected based on discrete correlation function, structure function as well as Jurkevich method. Correlations among different bands were also analyzed and no reliable time delay was found between optical bands. Very weak correlations were detected between V band and radio bands. However, in radio bands the variation at low frequency lagged that at high frequency obviously. The spectrum of BL Lacertae turned mildly bluer when the object turned brighter, and stronger bluer-when-brighter trends were found for short flares. A scenario including a precessing helical jet and periodic shocks was put forward to interpret the variation characteristics of BL Lacertae.Comment: 7 pages, 11 figures, submitte

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Section: Periodicity Analysissupporting

confidence: 59%

“…Then we used SF, a powerful and well-studied method for period analysis (Simonetti et al, 1985;Paltani et al, 1997;Gupta et al, 2008). Application of SF led to a periodogram shown in Fig.…”

Section: Periodicity Analysismentioning

confidence: 99%

Long-term optical and radio variability of BL Lacertae

Guo

et al. 2015

New Astronomy

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“…Over the last two decades, the optical variability of blazars has been extensively studied on diverse time‐scales (e.g. Heidt & Wagner 1996; Sillanpää et al 1996a,b; Ciprini et al 2003, 2007; Gupta et al 2004, 2008a,b,c; Gupta, Srivastava & Wiita 2009, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Optical intraday variability studies of 10 low energy peaked blazars

Rani

Gupta

Joshi

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We have carried out optical (R band) intraday variability (IDV) monitoring of a sample of 10 bright low energy peaked blazars (LBLs). 40 photometric observations, of an average of ∼4 h each, were made between 2008 September and 2009 June using two telescopes in India. Measurements with good signal‐to‐noise ratios were typically obtained within 1–3 min, allowing the detection of weak, fast variations using N‐star differential photometry. We employed both structure function and discrete correlation function analysis methods to estimate any dominant time‐scales of variability and found that in most of the cases any such time‐scales were longer than the duration of the observation. The calculated duty cycle of IDV in LBLs during our observing run is ∼52 per cent, which is low compared to many earlier studies; however, the relatively short periods for which each source was observed can probably explain this difference. We briefly discuss possible emission mechanisms for the observed variability.

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“…Over the last two decades, the optical/NIR variability of blazars has been extensively studied on diverse time‐scales (e.g. Miller, Carini & Goodrich 1989; Carini et al 1992; Courvoisier et al 1995; Heidt & Wagner 1996, Takalo et al 1996; Sillanpää et al 1996a,b; Bai et al 1998, 1999; Fan et al 1998; Xie et al 2002a; Gupta et al 2004, 2008a,b,c,d; Gupta, Srivastava & Wiita 2009; Stalin et al 2005, 2006; also Teräsranta et al 1992, 2004; Ciprini et al 2003, 2007; Rani, Wiita & Gupta 2009; and references therein). There are several theoretical models that might be able to explain the observed variability over wide time‐scales for all bands, with the leading contenders based upon shocks propagating down relativistic jets (e.g.…”

Section: Introductionmentioning

confidence: 99%

Short-term flux and colour variations in low-energy peaked blazars

Rani

Gupta

Strigachev

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We have measured multiband optical flux and colour variations for a sample of 12 low-energy peaked blazars (LBLs) on short, day-to-month, time-scales. Our sample contains six BL Lacertae objects (BL Lacs) and six flat spectrum radio quasars (FSRQs). These photometric observations, made during 2008 September to 2009 June, used five optical telescopes, one in India and four in Bulgaria. We detected short-term flux variations in 11 of these blazars and colour variability in eight of them. Our data indicate that six blazars (3C 66A, AO 0235+164, S5 0716+714, PKS 0735+178, OJ 287 and 3C 454.3) were observed in pre-or post-outburst states, five (PKS 0420−014, 4C 29.45, 3C 279, PKS 1510−089 and BL Lac) were in a low state, while one (3C 273) was in an essentially steady state. The duty cycles for flux and colour variations on short time-scales in these LBLs are ∼92 and ∼33 per cent, respectively. The colour versus magnitude correlations seen here support the hypothesis that BL Lac objects tend to become bluer with increase in brightness; however, FSRQs may show the opposite trend, and there are exceptions to these trends in both categories of blazar. We briefly discuss emission models for active galactic nuclei that might explain our results.

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Multi-color optical variability of the TeV blazar Mrk 501 in the low-state

Cited by 32 publications

References 48 publications

Long-term optical and radio variability of BL Lacertae

Long-term optical and radio variability of BL Lacertae

Optical intraday variability studies of 10 low energy peaked blazars

Short-term flux and colour variations in low-energy peaked blazars

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