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Dark Matters

Final Report Summary - DARK (Dark Matters)

This interdisciplinary proposal spanned theoretical astrophysics and particle physics by addressing the need to provide astrophysical expertise to the particle astrophysics community in the area of dark matter and dark energy research. A new dialogue was developed via collaborations involving expertise in astronomy, statistics and particle physics that centre on fundamental aspects of the nature of the contents of the universe. Identifying the nature of dark matter is one of the most urgent problems in cosmology. We refined theoretical predictions to pursue the quest for dark matter using novel experiments designed to detect the signatures of dark matter in our galactic halo both directly via scattering and indirectly via annihilations into high energy particles and photons. Dark matter and dark energy were studied by cosmic microwave background temperature fluctuations and structure formation constraints. The former probe was found to be contaminated by inadequately understood foregrounds that were examined to extract clues to new physics in the very early universe, rendered especially timely in view of the data from the Planck satellite. The latter is rendered difficult by the highly complex interface of star and galaxy formation. We emphasised development of feedback prescriptions, an ingredient that plays a central role in the current paradigm for galaxy formation and complements ultradeep searches with the new generation of telescopes. Our overall goal was to leverage, via the application of theory, the unprecedented experimental efforts that are underway to address dark sector issues in the emerging field of particle astrophysics. Some of the research highlights include the prediction of neutrino line signals from annihilating dark matter for future neutrino telescopes and predictions of gamma ray fluxes from central density spikes of dark matter that accumulate around the supermassive black hole at the centre of our galaxy and around the closest massive galaxy, M87. The connection between jets from active galactic nuclei and the surrounding interstellar gas has been found both to quench and to trigger star formation at different phases of cosmic history. Neutron stars have been shown to be powerful probes of dark matter. We studied the signatures of annihilating dark matter in the inner regions of galaxies where the dark matter is most concentrated. Dark matter signatures include distinct signals near supermassive black holes such as the imprint on the black hole shadow at the center of M87 that can be exploited by the Event Horizon telescope. Our modeling of galaxy formation has progressed enormously in recent years, but our understanding has not. Current theory is unable to make robust predictions of the properties of dwarf galaxies or of the evolution of Milky Way-type galaxies and their more massive early-type counterparts. Our approach has been to explore the role of supermassive black holes in galaxy formation. One of the most exciting and challenging predictions of positive, black-hole-induced, feedback on cosmic star formation is the generation of kinematic tracers in the stellar components in nearby galaxies. Our predictions will be explored with the new generation of instruments capable of spatially resolved spectroscopy with very large telescopes.