Jets in radio galaxies and quasars: an observational perspective

TL;DR

This review summarizes observational findings on jets in radio galaxies and quasars, focusing on their classification, structure, interaction with the environment, and implications for galaxy evolution, highlighting recent advances and open questions.

Contribution

It provides a comprehensive overview of observational evidence on jets, including recent results on classifications, interactions, and feedback mechanisms, emphasizing the role of new telescopes in future research.

Findings

Jets interact with the interstellar medium, influencing star formation.

Recurrent jet activity occurs over various scales and times.

Jets exhibit different structures in FR classes and excitation states.

Abstract

This article gives a brief historical introduction and reviews our current understanding of jets in radio galaxies and quasars from an observational perspective, with an emphasis on observations at radio wavelengths. Recent results on the Fanaroff-Riley classification scheme, and the nature of radio structures and jets in the FR classes as well as in high-excitation and low-excitation radio galaxies are summarized. The collimation and propagation of jets from nuclear sub-pc to hundreds of kpc scales from both observatinoal and theoretical work have been discussed. The jets exhibit evidence of interaction with a clumpy interstellar medium, especially in young radio sources, and could trigger both star formation as well as suppress star formation depending on the physical conditions. Observational evidence for such interactions and jet feedback which have profound implications in our understanding of galaxy evolution have been presented. Recurrent jet activity which has been seen over a wide range of projected linear size and time scales has been discussed. This review article concludes with a brief discussion of unresolved questions on jets which new telescopes should help address.