|Description:|| The evolutionary stage of a powerful radio source originated by an AGN is related to its linear size. In this context, compact symmetric objects (CSOs), which are powerful and intrinsically small objects (<1 kpc), should represent the young stage in the individual radio source life. Following the evolution models, these objects would evolve into the population of classical radio galaxies. However, the fraction of young radio sources in flux density-limited sample is much larger than what expected from the number counts of large radio sources, suggesting the existence of short-lived radio sources.|
The image shows the radio emission of a compact steep spectrum radio source with a double structure. The radio spectrum between 1 and 14 GHz of each component is steep and no indication of active regions is observed. These characteristics make this object a short-lived radio source candidate, whose radio emission is unlikely to evolve into a large classical radio galaxy.
The left panel shows the total intensity (contour) and polarized (colour-scale) emission of the radio source, obtained with the Jansky VLA at 14 GHz. Vectors represent the electric vector position angle.