Institute of Advanced Studies

Dark matter in galaxies

About 90 per cent of galaxies is invisible: we know it is there from its gravitational field but we do not yet know what it is.

Numerical simulations make definite predictions about the properties of dark matter in galaxies, but many of these predictions appear to be at odds with what we actually observe. I will talk about what we know about dark matter in galaxies, and describe some of the observational and conceptual problems.

Ken Freeman's research interests are in the formation and dynamics of galaxies and globular clusters, and particularly in the problem of dark matter in galaxies: he was one of the first to point out (1970) that spiral galaxies contain a large fraction of dark matter.

For his current research, he uses optical and radio telescopes in Australia and the USA, and also observes with the Hubble Space Telescope and large optical telescopes in Spain, Chile, and Hawaii. He has written about 750 research articles, and a book on dark matter, and was named by ISI in 2001 as one of Australia's most highly cited scientists.