A preferred orientation for large radio sources relative to their elliptical galaxies

Abstract

The relative orientations of 78 carefully selected radio sources and their parent elliptical galaxies have been determined. The radio structures are preferentially, but not exclusively, aligned toward the projected minor axes of the core (10-20 kpc) light distributions of the galaxies as seen on the red-sensitive print of the Palomar Sky Atlas. Furthermore, the trend toward this minor-axis alignment appears strongest among radio galaxies with linear extents greater than 250 kpc. It is suggested that alignment of the radio-source collimator with the core minor axis favors the development of radio lobes at large distances from the galaxies; this is most easily understood if most of the galaxies studied are oblate rotators at their cores.