Optical intraday variability studies of 10 low energy peaked blazars

Abstract

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.

Multicolor Optical Monitoring of the Quasar 3C 273 from 2005 to 2016

“…Small amplitude changes over a short time were reported (e.g. Moles et al 1986;Rani et al 2011). However, for the quasar, Fan et al (2009) also presented intra-day variations of 0.55 mag in 13 minutes and 0.81 mag in 116 minutes.…”

“…The observed radiation is predominantly non-thermal Doppler boosted jet emission enhanced by that arising from shocks in the flows (Marscher & Gear 1985). Models based on the instabilities on the accretion disk could yield IDV when the blazar is in the low state, because in the low state, any contribution from the jets is weak (Rani et al 2011). For the quasar, the instabilities on the accretion disk could yield IDV in the modest state because it has obvious blue-bump emission.…”

“…The flux and spectral variations of 3C 273 have been extensively studied over the entire electromagnetic spectrum (e.g. Xie et al 1999Xie et al , 2004aGhosh et al 2000;Mantovani et al 2000;Collmar et al 2000;Sambruna et al 2001;Greve et al 2002;Kataoka et al 2002;Courvoisier et al 2003;Jester et al 2005;Attridge et al 2005;Savolainen et al 2006;McHardy et al 2007;Soldi et al 2008;Espaillat et al 2008;Pacciani et al 2009;Dai et al 2009;Fan et al 2009Fan et al , 2014Abdo et al 2010;Ikejiri et al 2011;Rani et al 2011;Vol'vach et al 2013;Beaklini & Abraham 2014;Kalita et al 2015;Esposito et al 2015;Madsen et al 2015;Chidiac et al 2016). Soldi et al (2008) studied the multiwavelength variability of 3C 273.…”

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

“…In other words, microvariability is correlated with the flux gradients rather than specific flux states. Rani et al [14] reported the detection of microvariability with large DC in a sample of bright low-energy-peaked BL Lac sources (LBLs). Similarly, during their study of multiband optical flux and color variations of blazars on intraday and short term timescales of a few months, Gaur et al [15] found that the spectra of BL Lac sources often showed bluer-when-brighter trend whereas in flat spectrum radio quasars (FSRQ) the redder-when-brighter trend appears more frequent.…”

Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273

“…The source is categorized as a low synchrotron peaked blazar (LSP) by Abdo et al (2010a). The broadband spectrum, the correlation among multi-frequency flares, and the VLBI jet kinematics of the source were extensively studied in the past (e.g., Krichbaum et al 2001;Rani et al 2010Rani et al , 2011Soldi et al 2008;Savolainen et al 2010;Abdo et al 2010e, and references therein).…”