R-band imaging of fields around 1<z<2 radiogalaxies

Abstract

We have taken deep R-band images of fields around five radiogalaxies: 0956+47, 1217+36, 3C 256, 3C 324, and 3C 294, with 1<z<2. 0956+47 is found to show a double nucleus. Our data on 1217+36 suggest the revision of its classification as a radiogalaxy. We found a statistically significant excess of bright (19.5<R<22) galaxies on scales of 2 arcmin around the radiogalaxies (which have R 21.4) in our sample. The excess has been determined empirically to be at the 99.5% level. It is remarkable that this excess is not present for 22<R<23.75 galaxies within the same area, suggesting that the excess is not physically associated to the galaxies but due to intervening groups and then related to gravitational lensing.