Radial slope, γ_DM, of the dark matter halo as a function of the baryonic fraction in the Einstein radius, R_E. The colour code represents the value of  for all acceptable models, i.e.,  (see text; Eq. (6)). The observational limits drawn on f_b using our spectrum of the lensing galaxy are indicated as shaded vertical regions. The blue region corresponds to a Kroupa IMF and the red regions corresponds to a Salpeter IMF. In this figure, all models have r_s = 4  ×  R_E = 25 kpc.