Star formation in 3CR radio galaxies and quasars at z < 1
  Using the Herschel Space Observatory we have observed a representative sample
of 87 powerful 3CR sources at redshift z < 1. The far-infrared (FIR, 70-500
micron) photometry is combined with mid-infrared (MIR) photometry from the
Wide-Field Infrared Survey Explorer (WISE) and catalogued data to analyse the
complete spectral energy distributions (SEDs) of each object from optical to
radio wavelength. To disentangle the contributions of different components, the
SEDs are fitted with a set of templates to derive the luminosities of host
galaxy starlight, dust torus emission powered by active galactic nuclei (AGN)
and cool dust heated by stars. The level of emission from relativistic jets is
also estimated, in order to isolate the thermal host galaxy contribution. The
new data are in line with the orientation-based unification of high-excitation
radio-loud AGN, in that the dust torus becomes optically thin longwards of 30
micron. The low excitation radio galaxies and the MIR weak sources represent
MIR- and FIR-faint AGN population different from the high-excitation MIR-bright
objects; it remains an open question whether they are at a later evolutionary
state or an intrinsically different population. The derived luminosities for
host starlight and dust heated by star formation are converted to stellar
masses and star formation rates (SFR). The host-normalized SFR of the bulk of
the 3CR sources is low when compared to other galaxy populations at the same
epoch. Estimates of the dust mass yield a 1--100 times lower dust/stellar mass
ratio than for the Milky Way, indicating that these 3CR hosts have very low
levels of interstellar matter explaining the low level of star formation. Less
than 10% of the 3CR sources show levels of star formation above those of the
main sequence of star forming galaxies.
