Scientific report


The focus of the workshop was to bring together experts on various methods to measure masses of clusters of galaxies and to discuss the pros and cons of the techniques.Unfortunately an ash cloud produced by a volcanic eruption on Iceland shut down air travel, which led to the cancelation of approximately a third of the participants (trans-Atlantic and Italy) and prevented organizer Andisheh Mahdavi from attending.Fortunately the remaining participants were able to arrive by train and two talks were done through video conferencing. Importantly, the composition of the group of attendees was such that expertise in essentially all aspects of cluster mass determination remained. We were extremely pleased that, despite the travel troubles, we were able to cover all the topics of the workshop.


Nevertheless, the program was adjusted, with the Friday reserved for collaborative discussions and general interactions. Interestingly, due to the smaller size of the group, the discussions were extremely interactive. Also, the talks were very interesting, with the speakers providing honest assessments of the limitations of the various methods. Such frank discussions are not possible at a typical conference, and the more intimate setting of the Lorentz Center has to be credited for this. Therefore all present felt that the workshop was a sounding success.


The discussions demonstrated the impressive progress that has been made in both observations and numerical simulations and the need to connect both in order to interpret the impressive multi-wavelength data that have been, and are being, collected Ideas for a collaborative effort were discussed, but current data sets can still be managed by the various research teams that were present. Therefore there was little enthusiasm to expand current collaborations. Nonetheless the need for a follow-up meeting, with a focus on simulations and cluster physics, was recognized.


For many participants this was their first visit to the Lorentz Center and they were impressed with the facilities and the very efficient organization. Although the program was diverse, we felt that still more time for discussion would be needed (even with the reduction in talk we already experienced). Fortunately the Friday without talks allowed us to discuss various projects informally.


To summarize, despite being adversely affected by the flight-ban, the workshop turned out great. The small size of the group led to frank and interactive discussions. The only negative moment was the treatment of the participants in the cafeteria due to an obviious misprint on the lunch tickets. Rather than being welcomed as guests of the university we were considered “criminals” trying to get a free lunch...