Long term optical and infrared variability characteristics of Fermi Blazars

Abstract

We present long term optical and near infrared flux variability analysis of 37 blazars detected in the $\gamma$-ray band by the {\it Fermi Gamma-Ray Space Telescope}. Among them, 30 are flat spectrum radio quasars (FSRQs) and 7 are BL Lac objects (BL Lacs). The photometric data in the optical (BVR) and infrared (JK) bands were from the Small and Moderate Aperture Research Telescope System acquired between 2008$-$2018. From cross-correlation analysis of the light curves at different wavelengths, we did not find significant time delays between variations at different wavelengths, except for three sources, namely PKS 1144$-$379, PKS B1424$-$418 and 3C 273. For the blazars with both B and J-band data, we found that in a majority of FSRQs and BL Lacs, the amplitude of variability (${\sigma }_m$) in the J-band is larger than B-band consistent with the dominance of the non-thermal jet over the thermal accretion disc component. Considering FSRQs and BL Lacs as a sample, there are indications of ${\sigma }_m$ to increase gradually towards longer wavelengths in both, however, found to be statistically significant only between B and J-bands in FSRQs. In the B$-$J v/s J colour magnitude diagram, we noticed complicated spectral variability patterns. Most of the objects showed a redder when brighter (RWB) behaviour. Few objects showed a bluer when brighter (BWB) trend, while in some objects both BWB and RWB behaviours were noticed. These results on flux and colour characteristics indicate that the jet emission of FSRQs and BL Lacs is indistinguishable.

arXiv commentAccepted for publication in MNRAS

References in corpus (33)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter
• On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei
• BL Lac Objects in the Synchrotron Proton Blazar Model
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• A Proton Synchrotron Blazar Model for Flaring in Markarian~501
• Modeling the Emission Processes in Blazars
• SMARTS optical and infrared monitoring of 12 gamma-ray bright blazars
• The Fermi blazars divide
• A Universal Scaling for the Energetics of Relativistic Jets From Black Hole Systems
• Optical and radio behaviour of the BL Lacertae object 0716+714
• The dividing line between FR I and FR II radio--galaxies
• The WEBT BL Lacertae Campaign 2001 and its extension
• The Outburst of the Blazar S5 0716+71 in 2011 October: Shock in a Helical Jet
• The correlated optical and radio variability of BL Lacertae. WEBT data analysis 1994-2005
• Spectral Slope Variability of BL Lac Objects in the Optical Band
• An accretion disc model for quasar optical variability
• Optical Variability of Narrow and Broad line Seyfert 1 galaxies
• Multiwavelength Cross-Correlations and Flaring Activity in Bright Blazars
• The long-term optical spectral variability of BL Lacertae
• Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst
• Variability in Active Galactic Nuclei from Propagating Turbulent Relativistic Jets
• The nature of optical and near-infrared variability of BL Lacertae
• X-ray flux variability of active galactic nuclei observed using NuSTAR
• Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands
• Simultaneous MITSuME gRI monitoring of S5 0716+714
• Temporal correlation between the optical and γ-ray flux variations in the blazar 3C 454.3
• Long-term optical-infrared color variability of blazars
• Flux and polarization variability of OJ 287 during early 2016 outburst
• Optical Variability and Colour Behaviour of 3C 345
• Optical Variability of TeV Blazars on long time-scales
• Multi-color optical monitoring of ten blazars from 2005 to 2011
• Thermal AGN Signatures in Blazars

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• Optical Spectral Variations of a Large Sample of Fermi Blazars
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• Correlation between optical and $\gamma$-ray flux variations in BL Lacs
• Multi-wavelength Variation Phenomena of PKS 0735+178 on Diverse Timescale
• Multiband Optical Variability of the Blazar 3C 454.3 on Diverse Timescales
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• On the origin of multifrequency temporal and spectral variability in Ton 599
• Multiwavelength temporal and spectral study of TeV blazar 1ES 1727+502 during 2014 to 2021
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