Observations and Models of Multiwaveband Variability of Blazars

Multi-wavelength light curves of bright gamma-ray blazars (e.g., 3C 454.3) reveal strong correlations across wavebands, yet striking dissimilarities in the details. This conundrum can be explained if the major outbursts result from high-amplitude variations in the magnetic field and relativistic electron content in the jet flow, while the faster fluctuations are caused by turbulence in the flow. In the model developed by the author, much of the optical and high-energy radiation in a blazar is emitted near the 43 GHz core of the jet as seen in VLBA images, parsecs from the central engine, as indicated by observations of a number of blazars. This presentation will compare multi-waveband light curves of blazars, compiled by a world-wide collaboration that he leads, with simulated light curves produced by a numerical model that incorporates turbulent plasma - modulated by random fluctuations of the jet flow - crossing standing shocks that compress the plasma and accelerate electrons to highly relativistic energies.

This research is supported in part by NASA through Fermi grants NNX08AV65G, NNX10AO59G, and NNX11AQ03G, and by NSF grant AST-0907893.