Clusters and groups of galaxies – observations

Systems of galaxies (clusters anf groups) are the largest structures in the Universe in dynamical equilibrium. They contain from dozens (the groups) up to thousands (the clusters) of galaxies. The stellar component of these systems account for less than 5% of their total mass. X-ray observations show that most of the baryonic mass is in the plasma phase, at temperatures of several hundred kelvins. Dynamical analyses show that stars and plasma together only account for less than 20% of the total mass of these systems. Most of their mass does not emit electromagnetic radiation, it is probably non-baryonic, and is known as “dark matter”. The study of galaxy systems concerns several topics of extragalactic astrophysics: the estimate of cosmological parameters, the nature of dark matter, the properties of the large scale structure and of cosmological haloes, galaxy evolution in high-density environments, the physics of the intra-cluster medium.

Contact Person: A. Biviano

Staff: S. Borgani, G. De Lucia, M. Girardi P. Monaco, M. Nonino

PostDoc: E. Munari, B. Sartoris

PhD Students

GCAV - Galaxy Clusters at VIRCAM

Contact Person: M. Nonino