K-band polarimetry of seven high-redshift radio galaxies

We present the results of K-band imaging polarimetry of seven 3CR radio galaxies with 0.7 < z < 1.2. We find strong evidence for polarization in three sources: 3C 22, 3C 41 and 3C 114. Of these, 3C 41 shows strong evidence of having a quasar core whose infrared light is scattered by dust. We also find some evidence for polarization in 3C 54 and in 3C 356. The two pointlike sources (3C 22 and 3C 41) and the barelyelongated 3C 54 appear to have of order ten per cent of their K-band flux contributed by scattered light from the active nucleus. We conclude that scattered nuclear light can form a significant component of the near-infrared light emitted by high-redshift radio galaxies, and discuss models in which the scattering particles are electrons and dust-grains.