Neutral hydrogen in radio galaxies: results from nearby, importance for far away

Abstract

The study of neutral hydrogen emission and absorption in radio galaxies is giving new and important insights on a variety of phenomena observed in these objects. Such observations are helping to understand the origin of the host galaxy, the effects of the interaction between the radio jet and the ISM, the presence of fast gaseous outflows as well as jet-induced star formation. Recent results obtained on these phenomena are summarized in this review. Although the HI observations concentrate on nearby radio galaxies, the results also have relevance for the high-z objects as all these phenomena are important, and likely even more common, in high-redshift radio sources.