Evidence for radiation field collimation in NGC4151

Abstract

We report on a detailed study by the Lovers of Active Galaxies collaboration of the gas and dust surrounding the active nucleus in NGC4151. The ionization structure of the extended narrow line region (ENLR) is broadly consistent with photoionization by the AGN radiation field. The jet-like morphology of the ENLR, and its misalignment with the arcsecond-scale radio source, can be explained if ionizing radiation emerges from the nucleus in a broad inclined cone and illuminates the galactic disk at grazing incidence. The overall distribution of gas and dust suggests that bar-driven gas flows are important in the circum-nuclear region and that these are intimately linked to the material collimating the ionizing radiation field.