Final Report Summary - COSMOCOMP (Pan-European training in computational cosmology: modelling cosmic structures) Progress in cosmology has been made at a breath taking pace over the past 20 years, through observational breakthoughs including the first detections of temperature fluctuations in the cosmic microwave background radiation, a relic of the Big Bang, and huge maps of the galaxy distribution, and accompanying advances in the theoretical understanding of the evolution of the universe. Much of the theoretical progress has been underpinned by computer simulations of the growth of cosmic structures. The overall objective of the CosmoComp ITN is to provide a new European focus in this area, and to form a new body of highly trained young researchers.The main scientific goal of the network is to use computer simulations to understand the formation of cosmic structures, ranging from simulating the first objects in the Universe, through to the satellites of the Milky Way to the largest scale cosmic structures. The network has privileged access to world class supercomputer resources to achieve this aim. The CosmoComp ITN is built around existing collaborations, such as a sub-set of the Virgo Consortium for Cosmological Simulations (PIs Frenk at Durham and White at Garching) and smaller bilalteral collaborations (e.g. between Durham and Barcelona). However, many nodes had not collaborated with one another before CosmoComp. The ITN is therefore forstering completely new collaborations between the leading European research centres in computational cosmology, and raising the profile of Europe in this area.The scientific highlights to date of the CosmoComp ITN include:1) The completion of the first multi-hundred billion particle cosmological simulation, the Millennium-XXL (MXXL) N-body run. This calculation ran on 12288 cores on the JuRoPa machine at the Julich Supercomputing Centra in Germany, occupying 29 terabytes of RAM. The MXXL used 303 billion particles to represent the matter distribution in a cube 4286 Mpc on a side. Similar calculations have been carried out by the CSIC researchers and released to the Euclid Consortium to assist in their preparations for the construction and operation of the European Space Agency's dark energy mission, due for launch in 2020. 2) The development of a new state of the art of in gas dynamic modelling of galaxy formation, elucidating the physical processes that help to shape the evolution of the galaxy population over the history of the Universe. A series of ground breaking calculations have been carried out, including the Over-Whelming Large Simulations (OWLS) and culminating in the EAGLE simulation, which was completed shortly after the formal end of CosmoComp, and which involved several CosmoComp fellows. 3) Several studies of how baryonic physics, such as stellar and AGN feedback, affect the overall distribution of matter. This has important implications for cosmological probes such as weak gravitational lensing, which rely upon an accurate knowledge of the shape of the matter power spectrum down to scales corresponding to dark matter halos, and also for the interpretation of galaxy clustering measurements. 4) A possible first detection of the gamma-rays produced by the annihilation of dark matter particles (Han et al. 2012). The excess of gamma-rays from the nearby Coma cluster has other possible explanations, which are perhaps more likely, such as emission from active galactic nuclei. 5) CosmoComp researchers have helped to develop new state of the art codes in the hydrodynamical simulation of the physics of galaxy formation, including the moving mesh code AREPO, and an overhauled version of the smooth particle hydrodynamics code, GADGET. The latter has been used in the largest gas simulation run to date, the EAGLE project run, which has modelled the galaxy population in a representative volume of the Universe. Other novel codes have been developed and released to the wider community, such as the ECOSMOG upgrade to the adaptive mesh refinement code RAMSES. ECOSMOG is the only code which is able to solve in parallel the highly nonlinear equations which arise in modified gravity cosmologies, allowing us to investigate such models for the first time at the same level of detail as models which assume general relativity. 6) The CosmoComp ITN has been particularly active in galvanising the community to carry out comparisons of the calculation of fundamental quantities and statistics, such as the identification of dark matter haloes and the construction of merger histories, which are vital ingredients of galaxy formation models. CosmoComp achieved 97% if its ambitious recruitment target of 690 fellow months, comprised of 570 months of ESR and 120 months of ER. Over the period of the ITN, 32 researchers have been engaged in our training activities and research program. 24 of these were ESR and 8 ER. Females were particularly well represented as experienced researchers, accounting for 4 out of 7 posts and 56% of the fellow months. The balance was more inline with that in the subject as a whole for ESRs, in which case 6 out of 24 were female, accounting for 25% of fellow months. Training is delivered through a combination of 1) postgraduate programmes at the ITN nodes, 2)research internships, which provide specialised training by research, 3) research secondments toother nodes in the ITN, 4) new network wide training events, and 5) training provided by our industrial partners.A large number of network events, 15, were made possible by the support of the ITN. Besides the kick-off meeting and the mid-term review, the content and format of these events was driven by the fellows themselves. The fellows did an excellent job of organising these events. Three types of events took place. The first could be described as the traditional workshop format, in which progress on research projects was reviewed, giving ESRs and ERs experience of presenting their work. The second was particularly innovative and took the form of hands-on schools. These were put together by the fellows with the aim of developing a particular skill. The events were made up of a small number of talks delivered by experts who then designed and oversaw exercises carried out by the fellows working in small groups. Finally we held code/technique comparison workshops, in which the leading proponents in the subject were locked away for a week to understand and compare how a given quantity or statistic is computed. These events have been particularly productive, resulting in a substantial number of refereed publications and have helped to raise the profile of the ITN. Our fellows also attended the PhD Summer School organised by Mircosoft, one of our associatedindustrial partners. The project results have been widely disseminated through presentations at workshops and international conferences, including the main international conference in the subject held during 2011 (the "Galaxy Formation" conference at Durham), through our website (http://www.cosmocomp.dur.ac.uk) and through papers. At the time of compiling this report, there are 125 papers that have been published in the main peer reviewed journals in the subject, with a further 19 papers under review and available on the astro-ph preprint server. All of our publications are available free of charge through aXriv. These papers have already attracted over 1000 citations and have been accessed nearly 50 000 times online. The acknowledge the support of the EC through its funding of CosmoComp. A list of publications is maintained on our webpages: http://www.cosmocomp.dur.ac.uk/pub.htmlNew papers will be added to this list and we expect several tens of papers to be published following this report which acknowledge CosmoComp support. Project website: http://www.cosmocomp.dur.ac.uk/
