A dichotomy in radio jet orientations

Abstract

We examine the relative orientations of radio jets, central dust and stars in low-power (i.e., FR I and FR I/II) radio galaxies. We use the position angles of jet and dust to constrain the three-dimensional angle θ_DJ between jet and dust. For galaxies with filamentary dust 'lanes' (which tend to be misaligned with the galaxy major axis) the jet is approximately perpendicular to the dust structure, while for galaxies with elliptical dust distributions (typically aligned with the galaxy major axis) there is a much wider distribution of θ_DJ. The dust ellipses are consistent with being nearly circular thin disks viewed at random viewing angles. The lanes are likely warped, unsettled dust structures. We consider two scenarios to explain the dust/jet orientation dichotomy.