Stellar population gradients Age_L, [Fe/H]_L , and A_v, in logarithmic space as a function of stellar mass. BC03 and E-MILES, SSP models have been included. Open circles correspond to Illustris simulation measurements in the outer (1–2 R_eff) galaxy region (Cook et al. 2016). Dashed black lines show flat gradients. The six objects with peculiar profiles (Sect. 5.1) have been removed from the analysis.