Cosmology
It is now well accepted that the observed structure of our universe is best
reproduced in the presence of cold dark matter and dark energy. Within this
framework of a LCDM cosmology, structures form in a hierarchical
bottom up fashion. The size, range and completeness of observational
data increased recently using the latest generation of astronomical instruments, and
opened the so-called period of precision cosmology. Hence, the basic
parameters describing such a LCDM universe can be in principle determined with
a precision of ten per cent or better. In this hierarchical picture of structure
formation, small objects collapse first and then merge in a complex manner to
form larger and larger structures. To a first approximation, one can study the
formation of cosmic structures using N-body simulations which follow
the gravitational collapse of collision-less particles. However, with the possible
exception of gravitational lensing, observations mainly reflect the state of the
ordinary (baryonic) matter. Therefore, their interpretation in the framework of
cosmic evolution requires that we understand the complex, non-gravitational,
physical processes which determine the evolution of the cosmic baryons. The evolution
of each of the underlying building blocks within the hierarchical formation
scenario will contribute to the state and composition of the intra-cluster medium
by being seed for metal pollution, magnetic fields, high energy particles and energy.
Depending on their origin, these components will be blown out by jets, winds or
ram pressure effects and finally mixed with the surrounding intra-cluster medium. Some
of these effects will be naturally followed within hydrodynamic simulations (like
ram pressure effects), others have to be improved via effective models (like star
formation and related feedback and chemical pollution by supernova). Further
components like magnetic fields and high energy particles need additional modeling of
their injection processes and evolution, and also have to be self consistently coupled
with hydrodynamics. Here, cosmological simulations are a valuable probe
of our understanding of the underlying physical processes and harbor enormous
potential for the interpretation of observational data.
K.Dolag