Baryons in Dark Matter Halos

The existence of Dark Matter (DM) has been known since the 30's of the last century. The first cognitions from motions of galaxies in clusters and by the kinematics of individual galaxies were followed by systematic investigations, primarily via galaxy rotation curves. Since the mid 90's, observations can be confronted with models defined in specific galaxy formation scenarios, in particular with the output of numerical simulations performed in the framework of (Lambda) Cold Dark Matter (CDM). The great success of these models is that they reproduce the large-scale structure with great success, while they - maybe not surprisingly - seem to fail to be equally successful in describing the evolution of the universe on smaller, i.e. cluster and galaxy scales. These developments were parallelled by breathtaking advancements in cosmology. Since the precision measurement of the spectrum of the cosmic microwave background (CMB) with COBE, subsequent experiments devoted to the CMB anisotropy (Boomerang, WMAP) have led to what is called 'precision cosmology'. This implies that we are in the position of validating (numerical) models to a high degree. At the same time, we are witnessing amazing developments in observational astronomy, which allow to explore the universe back into the epoch of re-ionization, thereby subjecting models to further critical and crucial tests, the last steps expected to be taken in the near future. All of this looking nice at first glance, it does not mean that we may comfortably sit back and consider most of the riddles solved. In fact, it must be a worry to any astrophysicist that both, DM and Dark Energy remain nothing but hypotheses as long as no particle has been detected in lab experiments yet. Are they just 'epicycles' like those resorted to prior to Kepler to explain the motions of planets? Nearly ten years of critical validation of CDM models have, apart from a lot of success, resulted in what has been coined as the "first and second CDM crisis", i.e. the failure of theory to explain the mass spectrum of dark satellites around big galaxies on large scales, and the (partial) absence of cusps in the dense inner part of galaxy halos. This obviously calls for continuing efforts in both, observational and theoretical fields. The conference Baryons in Dark Matter Halos we announce here is jointly organized by the Bochum /Bonn graduate research school "Galaxy Groups as Laboratories of Baryonic and Dark Matter" and SISSA is meant to bring together experts from the whole world working in the fields outlined above, trying to make a critical assessment of what has been achieved and to identify the problems that we are faced with. Invited reviews will be given to summarise the state-of-the-art, in particular to the participating graduate students and to scientists working in these fields. The event will provide the participating students with the opportunity to present their own work and advertise it to other participants. Their activity should also be understood as a stimulus for future collaborations or intensify the existing ones. In this sense, the event is meant to be between a summer school and a workshop. We would like that this meeting, that takes place in the inviting and picturesque location of Cittanova/Novigrad, Istria, will be featured by the same spirit present in many of the previous meetings and workshops of the graduate school. Our first aim for the five-day meeting is that the so-called "paradigm of hierarchical structure formation" be subjected to a lively and critical discussion (with strong involvement of the students!). A second aim is to identify future directions of research leading to further progress in our understanding of structure formation and evolution of galaxies. It is our aim that during the five-day meeting that the so-called paradigm of hierarchical structure formation will be subjected to a lively and critical discussion (with strong involvement of the students!), with the cosmological concordance model in the background. Future directions of research shall be identified that will lead to further progress in understanding structure formation and the evolution of galaxies. We hope that this meeting, taking place in the inviting location of Cittanova/Novigrad at the picturesque Istrian coast of Croatia, will be featured by the same spirit as was present in many of the previous meetings and workshops of the graduate school.