Astrophysics & Cosmology Sabine Schindler Institute for Astrophysics University of Innsbruck

Currently most active field of research in Innsbruck: Clusters of Galaxies  Largest bound structures  Size ~ a few Mpc  Mass ~ M sun  Observable to large distances Ideal tools for cosmology

Cluster Components  Galaxies  Intra-cluster gas – Density ~ – cm -3 – Temperature ~ K – Thermal bremsstrahlung  X-ray emission luminosity ~ erg/s optical X-rays

Mass fraction Observable in Galaxies3 – 5 %Optical Intra-cluster gas15 – 20 %X-rays Dark matterRest- We can measure  amount of dark matter  distribution of dark matter but nature of dark matter still unknown!!!

Matter Density  m of the Universe  Assumption: ratio of visible matter to dark matter in clusters is representative for the universe as a whole in units of the critical density

Structure Formation Observations only snapshots (time scales ~ 10 9 yrs) Numerical simulations follow the evolution Different components  galaxies, dark matter N-body  gas hydrodynamic simulations

For movies see

Comparison with Observations X-rays: XMM-Newton (ESA) De Filippis, Schindler, Castillo-Morales, 2003 optical: VLT (ESO) Erben, Miralles, Schindler, Schneider, in prep.

From observations and simulations: Dynamics Evolution Interaction of components Heavy element enrichment..... Structure Formation and Evolution Cosmology Galaxy clusters – the largest bound structures in the universe