ST images of B2 radio galaxies: a link between circum-nuclear dust and radio properties?

Almost 60% of the B2 low luminosity radio galaxies have been observed with the Hubble Space Telescope. We present an analysis of the dust features, which are often present in the form of circum-nuclear disks or lanes, and show that there are correlations between radio source and dust properties. It is found that nearby radio sources in which a jet has been detected tend to have dust more often than sources without jets; the dust is often in the form of disks or lanes. Moreover the radio jets are close to perpendicular to the disk or lane in the weaker radio sources (with P < 1024 WHz-1). In stronger sources the orientation effect appears to be weak or even absent. Also the dust masses found in the weaker radio sources are smaller than in the stronger ones (log M/Msun ~ 3 against 5 respectively). More generally it appears that there is a correlation between dust mass and total radio power (for those sources in which dust has been detected); we show that this correlation is not induced by redshift. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555 and by STScI grant GO-3594.01-91A.