Three questions for dark matter

Speaker:Professor Matthias Bartelmann
Affiliation:Institute for Theoretical Astrophysics, Heidelberg
Parent Event:Gravitational Lensing
Location:Lidow Rosen Auditorium (323)

Recently, the Planck satellite has spectacularly confirmed the standard model of cosmology. It is a strikingly simple model for the structure and evolution of the Universe which agrees with virtually all cosmological observables. However, it comes at a high price: according to this model, most of the matter in the Universe is of an unknown, "dark" form, and most of the energy content is not even contributed by matter.

The most common hypothesis asserts that dark matter is composed of massive, weakly interacting particles. Numerical simulations unanimously show that gravitationally bound structures composed of such particles should adopt density profiles with a universal form and a characteristic scale. These simulations also assert that dark matter should be clumped on (almost) arbitrarily small scales. Do gravitationally bound structures populating the real universe agree with these simulations? Recent, detailed and highly resolved observations based on gravitational light deflection do indeed seem to confirm the theoretical expectation shaped by simulations.

The question remains open why gravitationally bound structures of dark-matter particles should develop universal density profiles and what processes define the universality as well as the scales occurring. The talk will end suggesting a new approach towards clarify these issues.