Excesses of faint galaxies around seven radio QSOs at 1.0 < z < 1.6 - Clustering at high-z

We have conducted an optical study of the environments of seven radio-loud quasars at redshifts 1 < z < 1.6. In this paper we describe deep B and R ba nd images obtained for fields of similar to 6 x 6 arcmin around these quasa rs with 3 sigma limiting magnitudes of B similar to 26 and R similar to 25. 4. We found an statistically significant excess of faint(B > 22.5 and R > 2 2.0) galaxies on scales of r <170 " and r <35 " around the quasars. The num ber of excess galaxies, their magnitudes and the angular extension of the e xcesses are compatible with clusters of galaxies at the redshift of the QSO s. We also found that the quasars of our sample are in general not located at the peak of the density distribution, lying in a projected distance of a bout similar to 70 " from it. This result agrees with the scenario of a lin k between overdensities of galaxies around radio sources and the origin of their radio emission.