Large-scale H I structures and the origin of radio galaxies

We present the first results of a study aimed to detect large H I structures in radio galaxies. In two of the three cases presented (Coma A and B2 0648+27), the detection of a large amount of H I distributed over several tens of kpc suggests a major merger as the origin of the observed system and allows us to infer when this merger must have occurred. The situation is less clear for the third object (3C 433). We propose an evolutionary sequence for one of the radio galaxies studied. The implications of this study of neutral hydrogen in nearby radio galaxies for high-<F>z</F> objects and ‘normal’ (i.e. radio-quiet) elliptical galaxies are also discussed. [Copyright &y& Elsevier]