Arc Second Structure of Compact Radio Sources

Abstract

Radio sources which have the majority of their emission arising from regions ≲ 2 arc sec in diameter are relatively common, forming approximately 30% of all strong sources in surveys made at ∿ 1 GHz. Compact sources usually have high radio luminosities and are found at high redshifts. At such distances the linear scales being discussed are ≲ 20 kpc so the majority of the radio emission arises within the parent galaxy. Some of the sources have prominent jets. These are invariably one-sided and often show quite large changes in position angle of elongation at different angular scales. We are interested in the causes of the one-sidedness (whether Doppler favouritism or not) and of the bends (whether due to winds or ballistic). In the ballistic case the apparent bends are due to precession or rotation of the central massive object and information of fundamental importance about the object may be deduced. Alternatively, if the bending is due to an interaction of the jet with its surroundings the bendings becomes a useful probe of the galactic environment.