The Dynamic Evolution of Young Extragalactic Radio Sources

TL;DR

This paper investigates the evolution and morphology of young extragalactic radio sources, especially compact symmetric objects (CSOs), analyzing their dynamics and how they relate to different physical processes and evolutionary stages.

Contribution

It provides a detailed analysis of CSO dynamics based on a sample of 24 sources, highlighting their evolutionary behavior and the factors influencing their morphology and development.

Findings

Radio power and hotspot separation velocities align with self-similar models.

Many CSOs do not evolve into larger radio sources.

Individual source behavior varies significantly from group trends.

Abstract

The evolution of symmetric extragalactic radio sources can be characterized by four distinct growth stages of the radio luminosity versus size of the source. The interaction of the jet with the ambient medium results in the formation and evolution of sources with non-standard (flaring) morphology. In addition, cessation or restarting of the jet power and obstruction of the jet will also result in distinct morphological structures. The radio source population may thus be classified in morphological types that indicate the prevailing physical processes. Compact symmetric objects (CSOs) occupy the earliest evolutionary phase of symmetric radio sources and their dynamical behavior is fundamental for any further evolution. Analysis of CSO dynamics is presented for a sample of 24 CSOs with known redshift and hotspot separation velocity and with a large range of radio power. Observables such as radio power, separation between two hotspots, hotspot separation velocity, and kinematic age of the source are found to be generally consistent with the self-similar predictions for individual sources that reflect the varying density structure of the ambient interstellar medium. Individual sources behave different from the group as a whole. The age and size statistics confirm that a large fraction of CSOs does not evolve into extended doubles.