The Occurrence/Non-occurrence of Dark Matter in Elliptical Galaxies
Wednesday, 02 December 2015 1 p.m. — 2 p.m. MST
AURA Lecture Hall
While dark matter is an indispensable ingredient in standard theories of cosmological structure formation, the direct evidence for dark matter through the dynamics of galaxies leads to confusion. The flat rotation curves of spiral galaxies can hardly be understood without dark matter, if one wants to avoid modifying gravity. The situation for elliptical galaxies is more complicated because of the missing disk symmetry. One has to analyse the integrated light projected along an extended line of sight and for larger radii has to rely on dynamical tracers like globular clusters and planetary nebulae.
I summarize our present knowledge of dark matter in elliptical galaxies in various environments from central cluster galaxies to isolated ellipticals. There is evidence that the MONDian phenomenology of galaxy dynamics also extends to elliptical galaxies. I introduce in some detail our programme of investigating isolated elliptical galaxies and present first results which are difficult to reconcile with the standard theory of galaxy formation in dark matter halos.