Dark Matter in the Elliptical Galaxies NGC 1399 and NGC 4636

We have used the multi–object spectrographs FORS2/MXU at the VLT and GMOS at Gemini South to obtain medium–resolution spectra of 625 and 437 globular clusters (GCs) around the giant elliptical galaxies NGC 1399 and NGC 4636, respectively. By measuring the radial velocities of a large sample of GCs, we determine the line–of–sight velocity dispersion as a function of projected galactocentric radius. These values are then compared to Jeans–models under different assumptions for the orbital anisotropy aswell.