New Evidence for an Anisotropic Radiation Field in NGC 5252

Observational evidence accumulated over the last decade strongly supports the idea that the ionizing radiation field in active galactic nuclei (AGNs) is anisotropic. Here we report on new evidence for this anisotropy in the particular case of the Seyfert 2 galaxy NGC 5252. H I observations of this galaxy reveal neutral gas surrounding the nucleus but located outside the bicone of ionized gas that notably characterizes this object. The neutral gas is at a distance from the nucleus where it could be reached by the ionizing radiation if this were isotropically distributed.