Jets from Sub-Parsec to Kiloparsec Scales: A Physical Connection

The Chandra discovery of bright X-ray emission from kpc-scale jets allows insight into the physical parameters of the jet flow at large scale. At the opposite extreme, extensive studies of the inner relativistic jets in Blazars with multiwavelength observations, yield comparable information on sub-parsec scales. In the framework of simple radiation models for the emission regions we compare the physical parameters of jets on these two very different scales in the only two well studied Blazars for which large-scale emission has been resolved by Chandra. Notably, we find that the relativistic Doppler factors and powers derived independently at the two scales are consistent, suggesting that the jet does not suffer severe deceleration or dissipation. Moreover the internal equipartition pressures in the inner jet and in the external X-ray bright knots scale inversely with the jet cross section as expected in the simple picture of a freely expanding jet in equipartition.