Outflows of neutral (and ionized) gas in radio galaxies

Abstract

Outflows up to 1500 km/s of atomic neutral hydrogen are detected in a growing number of radio galaxies. Outflows with similar velocities are also detected in ionized gas, suggesting a common origin for the extreme kinematics of these two phases of the gas. The high detection rate ofsuch outflows in young (or restarted) radio sources appears to be related to the existence of a dense ISM around these objects. Such a dense ISM can have important consequences for the evolution of the radio source and the galaxy as a whole. Here we summarize the recent results obtained and the characteristics derived so far for these outflows. We also discuss possible mechanisms (e.g. interaction between the radio plasma and the ISM and adiabatically expanding broad emission lines clouds) that can be at the origin of these phenomena.