Περίληψη :
Compact Symmetric Objects (CSOs) are a class of compact jetted Active Galactic Nuclei (AGN) whose observed emission is not relativistically boosted towards us. We compiled a catalog of 79 bona fide CSOs. Using our newly defined complete samples, we conclusively demonstrate that most CSOs do not evolve into larger-scale radio sources, but rather form a distinct population of jetted AGN that is short-lived and has a sharp upper cutoff in the size distribution at ~500 pc. The transient nature of most CSOs and their birthrate can be explained through ignition in the Tidal Disruption Events (TDEs) of giant stars. We demonstrate that there are two unrelated classes of CSOs: an edge-dimmed, low-luminosity class (CSO 1) and an edge-brightened, high-luminosity class (CSO 2) that can be further divided into three sub-classes. The four classes occupy different, but overlapping, portions of the luminosity-size plane. The luminosity-size plane can be interpreted – analogous to the Hertzsprung-Russel-Diagram for stars – as depicting a population of CSOs in different evolutionary stages, where CSO 2s evolve from CSO 2.0s, which are young and active, through CSO 2.1s into CSO 2.2s, which are old and fading. All of the above considerations make it clear that the joint study of jetted TDEs and CSOs provide a unique perspective on the complete life-cycle of relativistic jets.
