Multi-band optical-NIR variability of blazars on diverse timescales

Abstract

To search for optical variability on a wide range of timescales, we have carried out photometric monitoring of two flat spectrum radio quasars, 3C 454.3 and 3C 279, plus one BL Lac, S5 0716+714, all of which have been exhibiting remarkably high activity and pronounced variability at all wavelengths. CCD magnitudes in B, V, R and I pass-bands were determined for $\sim$ 7000 new optical observations from 114 nights made during 2011 - 2014, with an average length of $\sim$ 4 h each, at seven optical telescopes: four in Bulgaria, one in Greece, and two in India. We measured multiband optical flux and colour variations on diverse timescales. Discrete correlation functions were computed among B, V, R, and I observations, to search for any time delays. We found weak correlations in some cases with no significant time lags. The structure function method was used to estimate any characteristic time-scales of variability. We also investigated the spectral energy distribution of the three blazars using B, V, R, I, J and K pass-band data. We found that the sources almost always follows a bluer-when-brighter trend. We discuss possible physical causes of the observed spectral variability.

Accepted for publication in MNRAS, 16 pages, 11 figures, 5 tables, plus supplementary material containing additional figures and tables (please contact authors for it)

References in corpus (9)

• Periodic Oscillations in the Intra-day Optical Light Curves of the Blazar S5 0716+714
• Optical Intra-day Variability in Blazars
• The WEBT Campaign on the Blazar 3C279 in 2006
• AGILE detection of a strong gamma-ray flare from the blazar 3C 454.3
• Multi-band optical variability studies of BL Lacertae
• A multi-zone model for simulating the high energy variability of TeV blazars
• Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst
• Multi-color Near Infra-red Intra-day and Short Term Variability of the Blazar S5 0716+714
• Particle diffusion and localized acceleration in inhomogeneous AGN jets - Part I: Steady-state spectra

Cited by in corpus (20)

• Multi-band optical variability of three TeV Blazars on Diverse Timescales
• Multiband optical variability of the blazar OJ 287 during its outbursts in 2015 -- 2016
• Multi-band optical variability of the Blazar S5 0716+714 in outburst state during 2014-2015
• The complex variability of blazars: Time-scales and periodicity analysis in S4 0954+65
• Multi-wavelength Intra-day Variability and Quasi-periodic Oscillation in Blazars
• Characterizing optical variability of OJ 287 in 2016 - 2017
• The ever-surprising blazar OJ 287: multi-wavelength study and appearance of a new component in X-rays
• Multi-band optical variability of 3C 279 on diverse timescales
• Peak of spectral energy distribution play an important role in intra-day variability of Blazars?
• Multi-color optical monitoring of ten blazars from 2005 to 2011
• X-ray Intraday Variability of the TeV Blazar Mrk 421 with {\it Chandra}
• The Variability and Period Analysis for the BL Lac AO 0235+164
• Kepler light curve analysis of the blazar W2R 1926+42
• Multiband optical flux density and polarization microvariability study of optically bright blazars
• Optical Variability of Three Extreme TeV Blazars
• Characterizing the optical nature of the blazar S5 1803+784 during its 2020 flare
• Multi-wavelength study of TeV blazar 1ES 1218+304 using gamma-ray, X-ray and optical observations
• Multi-band Optical Variability of the TeV Blazar PG 1553+113 in 2019
• Multiband Optical Variability of the Blazar 3C 454.3 on Diverse Timescales
• Optical Monitoring and Long-term Optical Spectral Variability of BL Lacertae Object S5 0716+714