Bowshocks and the formation of the narrow-line region of Seyfert galaxies

Abstract

Considerable evidence exists for a relationship between the optical narrow-line region (the NLR) and the nuclear non-thermal radio emission in Seyfert galaxies. In a previous paper we introduced a model for the NLR, which we here develop and describe more fully, in which the linear motions of the radio components drive bowshocks into the ambient nuclear medium. The cooled shocked gas, photoionized by the UV nuclear continuum, produces the optical NLR emission. The radio components may take the form of bubbles of plasma ejected from the nucleus, or may represent the working surfaces of jets