Large Gas Disks in Radiogalaxies

Large-scale (up to 100 kpc) H I structures have been found in three radio galaxies using the WSRT and the VLA. In one case, the H I has been detected in emission while in the other two H I absorption is detected against the radio lobes. In at least two of the three studied radio galaxies the H I appears to be distributed in a large disk and the large amount of neutral gas detected (> ∼ 10 M⊙) indicates that it is resulting from mergers of gas-rich galaxies. The relatively regular structure and kinematics of these disks suggest that the merger must have happened more than 10 yrs ago, therefore supporting the idea that the radio activity starts late after the merger. In these low redshift radio galaxies we may witness the processes that are more efficiently and frequently happening at high-z.