Involved people at OAB: de Ruiter, Murgia.
De Ruiter is involved in various projects aimed at studying the physical properties of radio galaxies.
It has now been established that also radio jets in low luminosity radio galaxies (Fanaroff-Riley type 1) are relativistically beamed close to the nucleus, but quickly decelerate (in contrast with high luminosity radio galaxies) to become, after a few kpc, non-relativistic, mildly supersonic outflows. A statistical study of B2 radio galaxies by Laing, ..., de Ruiter, et al. (1999, MNRAS, 306, 513) shows that the small scale brightness asymmetries are in complete agreement with this picture.
Murgia et al. studied the radiative ages of low luminosity radio galaxies by interpreting spectral steepening as being due to the aging of synchrotron emitting electrons. Although the subject of synchrotron aging remains controversial, a coherent picture emerges, in which radio source regions with different radio spectral indices can be interpreted as representing different phases in the life of a radio source (Murgia, ..., de Ruiter, et al 1999, A&A, 344, 7).
With the Hubble Space Telescope snapshot images in V and I were obtained (so far) for about 60 % of the B2 sample of low luminosity radio galaxies. An article presenting these images has been submitted to A&A (Capetti (Observatory of Torino), de Ruiter, et al. 2000). Almost two thirds of the galaxies show dust features, very often in the form of dust bands or circumnuclear disks, and further study will reveal if there is any relation between the properties of the radio source and the dust.