We compute the galaxy luminosity function in spectroscopically selected nearby groups and clusters .
Our sample comprises 728 systems extracted from the third release of the Sloan Digital Sky Survey in the redshift range 0.03 < z < 0.06 with virial mass range 10 ^ { 11 } M _ { \odot } < M _ { vir } < 2 \times 10 ^ { 14 } M _ { \odot } .
In order to compute the galaxy luminosity function , we apply a statistical background subtraction method following usually adopted techniques .
In the r band , the composite galaxy luminosity function shows a slope \alpha = -1.3 in the bright–end , and an upturn of the slope in the faint–end , M _ { r } \ga - 18 + 5 log ( h ) , to slopes -1.9 < \alpha < -1.6 .
We find that this feature is present also in the i,g and z bands , and for all explored group subsamples , irrespective of the group mass , number of members , integrated color or the presence of a hot intra-cluster gas associated to X-ray emission .