Blazars exhibit the most extreme variability of the class of objects known as active galactic nuclei (AGN). They are characterized by a featureless continuum, high polarization, and variability at all wavelengths and time-scales. The amplitude of optical variations can range from less than 0.1 magnitude on time-scales of minutes to hours, to greater than 5.0 magnitudes on time-scales of months to years. Gamma-ray variability amplitudes can span a range of as much as three orders of magnitude on a time-scale as short as a few days. These characteristics are consistent with a supermassive black hole accreting matter at the heart of the host galaxy. However, the observed properties of these objects don't necessarily reflect the intrinsic properties because the emissions have been modified by their propagation over cosmological distances.
The intrinsic variability of 7 blazars, which have very different redshifts, have been investigated using several different analytical approaches; i.e., structure function analysis, variability index analysis, and light curve analysis. By transforming observed measurements into the rest frame of the source, the intrinsic properties of the variability can be compared. These variability characteristics of blazars, as seen in their rest frame, and as a function of state, are discussed in reference to their general characteristics and classification schemes.
In addition to the intrinsic variability investigation, a multi-color variability investigation has been undertaken. This investigation utilizes new data collected through the SMARTS (Small and Moderate Aperture Research Telescope System) consortium simultaneously in both the optical and near-infrared (near-IR) wavebands. The 11 objects in this sample, which have very different redshifts, are investigated using light curve analysis and color index analysis to determine if there exists any changes in color as a function of time (leads or lags) or variability amplitude.
The results from both investigations allow constraints to be placed on the location and nature of the emitting regions (e.g. variability originating from turbulence in the jet versus flares in an accretion disk).