It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. However, the size of the emitting zone and the location of this region relative to the central supermassive black hole are poorly understood. Here, the coincidence of a γ-ray flare with a dramatic change of optical polarization angle is reported, providing evidence for co-spatiality of optical and γ-ray emission regions and indicating a highly ordered jet magnetic field.
- A. A. Abdo
- M. Ackermann
- M. Sikora
