Astrophysical signatures of dark matter: its nature, the structure of haloes, and galaxy formation

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One of the most remarkable achievements of modern cosmology is the measurement of the fundamental constituents of the Universe. It is now well established that ordinary matter can only account for a mere 4 per cent of the total energy density. The vast majority (about three quarters) is believed to be in the form of a mysterious “dark energy”, while the remaining 21 per cent is composed of so-called “dark matter” particles.Yet, despite the ever increasing amount of astrophysical and cosmological evidence for its existence, dark matter has so far eluded direct detection in particle accelerators and recoil experiments. Thanks to the recent advances in instrumentation, indirect detection through the emission of radiation and relativistic particles has emerged as an interesting alternative, and many theoretical studies have been devoted to investigate the conditions under which dark matter particles would effectively become “visible”.The somewhat surprising conclusion of most of these works is that signatures are indeed expected on astrophysical scales, and in most cases they are within reach of present (INTEGRAL, COMPTEL/EGRET) or planned (GLAST, Planck) observatories. In fact, current data can already impose constraints on both the physical properties of dark matter and on its distribution within galaxies. It is the aim of the present project to make a systematic study of the emission expected for different dark matter models, its detectability by present and forthcoming instruments, and its possible impact on galaxy formation and evolution, in an attempt to address the basic question “What is dark matter?”.