SMARTS OPTICAL AND INFRARED MONITORING OF 12 GAMMA-RAY BRIGHT BLAZARS

Abstract

We present multiwavelength data for 12 blazars observed from 2008 to 2010 as part of an ongoing optical–infrared
\nphotometric monitoring project. Sources were selected to be bright, southern (δ < 20◦) blazars observed by the
\nFermi Gamma-Ray Space Telescope. Light curves are presented for the 12 blazars in BVRJK at near-daily cadence.
\nWe find that optical and infrared fluxes are well correlated in all sources. Gamma-ray bright flat spectrum radio
\nquasars (FSRQs) in our sample have optical/infrared emission correlated with gamma-rays consistent with inverse
\nCompton-scattering models. In FSRQs, variability amplitude increases toward IR wavelengths, consistent with the
\npresence of a thermal accretion disk varying on significantly longer timescales than the jet. In BL Lac objects,
\nvariability is mainly constant, or increases toward shorter wavelength. FSRQs have redder optical–infrared colors
\nwhen they are brighter,whileBLLac objects showno such trend. Several objects showcomplicated color–magnitude
\nbehavior: AO 0235+164 appears in two different states depending on its gamma-ray intensity. OJ 287 and 3C 279
\nshow some hysteresis tracks in their color–magnitude diagrams. Individual flares may be achromatic or otherwise
\ndepart from the trend, suggesting different jet components becoming important at different times. We present a
\ntime-dependent spectral energy distribution of the bright FSRQ 3C 454.3 during its 2009 December flare, which is
\nwell fit by an external Compton model in the bright state, although day-to-day changes pose challenges to a simple
\none-zone model. All data from the SMARTS monitoring program are publicly available on our Web site.