A Consolidated Framework of the Color Variability in Blazars: Long-Term Optical/Near-Infrared Observations of 3C 279

Abstract

We evaluate the optical/near-infrared (OIR) color variability of 3C 279 in both gamma-ray flaring and non-flaring states over 7-year timescales using the Small and Medium Aperture Research Telescope System (SMARTS) in Cerro Tololo, Chile and gamma-ray fluxes obtained from the Fermi Gamma-ray Space Telescope. This observing strategy differs from previous blazar color variability studies in two key ways: 1) the reported color variability is assessed across optical through near-infrared wavelengths, and 2) the color variability is assessed over timescales significantly longer than an individual flare or ground-based observing season. We highlight 3C 279 because of its complex color variability, which is difficult to reconcile with the simple "redder when brighter" behavior often associated with Flat Spectrum Radio Quasar (FSRQ) color variability. We suggest that the observed OIR color changes depend on a combination of the jet and disk emission. We parameterize this behavior in terms of a single variable, ${\zeta }_n^m$, representing a smooth transition from disk-dominated, to a mixed contribution, to a jet-dominated system, which provides an explanation of the long-term OIR color variability in the same blazar over time. This suggests a general scheme that could apply to OIR color variability in other blazars.

Accepted to the Astrophysical Journal (ApJ)

References in corpus (5)

• Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
• A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
• Multi-colour optical monitoring of eight red blazars
• Results of WEBT, VLBA and RXTE monitoring of 3C 279 during 2006-2007
• Polarization Swings Reveal Magnetic Energy Dissipation in Blazars

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