Dark matter in the elliptical galaxies NGC 1399 and NGC 4636

Abstract

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. © 2009 Springer-Verlag Berlin Heidelberg.