Prof. Dr. Matthias Bartelmann

Universität Heidelberg

On the similarity of cosmic structures

The Universe is filled with structures of vastly different scales: 
galaxies themselves span many orders of magnitude in mass and size; they agglomerate in galaxy groups and clusters; and they align along filaments tens of millions of lightyears long. Notwithstanding their vastly different sizes, gravitationally bound structures are internally very similar: for example, the radial profiles of their dominant, dark-matter density differ by scale, but not by shape. Why is this so, and what can we learn from this kind of universality? Does it depend on the nature of dark matter, details of the cosmological model, or of gravity theory? The talk will discuss approaches to these questions, present partial answers, and lead to conjectures about cosmic structures that remain to be tested.