Decoding the giant extragalactic radio sources

Giant radio sources (GRSs) defined to be >0.7 Mpc are the largest single objects in the Universe and can be associated with both galaxies (GRGs) and quasars (GRQs). They are important for understanding the evolution of radio galaxies and quasars whose sizes range from pc to Mpc scales and are also valuable probes of their environment. These radio-loud active galactic nuclei (RLAGN) interact with the interstellar medium of the host galaxy on small scales and the large-scale intracluster or intergalactic medium for the GRSs. With several new and sensitive surveys over the last few years, the number of known GRSs has increased many fold, which has led a resurgence of interest in the field. This review article summarises our current understanding of these sources based on nearly five decades of research, and discusses the importance of the Square Kilometer Array (SKA) in addressing some of the outstanding questions.