Rapid Variability of Gamma-ray Emission from Sites near the 43 GHz Cores of Blazar Jets

Understand

Comprehensive VLBI and multi-waveband monitoring indicate that a single superluminal knot can cause a number of gamma-ray flares at different locations.

• However, the often very rapid variability timescale is a challenge to theoretical models when a given flare (perhaps the majority of those observed) is inferred from observations to lie near the 43 GHz core, parsecs from the central engine.
• We present some relevant observational results, using the BL Lac object AO 0235+164 as an example.
• We propose a turbulent cell model leading to a frequency-dependent filling factor of the emission region.