NAOC Colloquium No.26 2023
|Small-scale dark matter structure / 暗物质的小尺度结构
|Prof.Simon D.M. White (Max-Planck-Institute)
|Tuesday, 2:30 PM, Nov.21, 2023
|NAOC A601 & Live Streaming on NAOC WeChat Channel
|Prof. Qi Guo / 郭琦 (NAOC)
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|Click to watch the video (later)
|The standard paradigm for cosmic structure formation has strong observational support on scales ranging from that of the entire observable universe down to those on which dwarf galaxies form. On all these scales, structure formation is driven by the gravitational effects of dark matter of unknown nature. Viable elementary particles candidates are constrained to behave like Cold Dark Matter on observed scales but a wide range of behaviours is possible on scales comparable to and smaller than the smallest dwarf galaxies. Numerical simulations allow exploration of dark matter structure on scales smaller than any visible object. On most scales dark matter halos form with a simple universal structure, but the very first nonlinear collapses produce objects with a different structure, so-called prompt cusps. For most dark matter candidates, the masses of these prompt cusps are too small for them to have measurable dynamical effects on visible systems, but their densities are so high that the majority will survive until the present day. As a result, their aggregate emission will dominate any gamma-ray signal from dark matter annihilation. This has important consequences for programmes aiming to detect dark matter indirectly through this signal, significantly strengthening the upper limits on annihilation cross-section implied by current observational data.
|Prof. Simon D. M. White is the Emeritus Director at the Max-Planck-Institute fuer Astrophysics, the Foreign Member of the Chinese Academy of Sciences , the Fellow of the Royal Society and the Foreign Associate of the US National Academy of Sciences. He is known for his contributions to understanding the structure formation in the Universe, his role in establishing the standard cosmological model, and his contributions to the understanding of galaxy formation and evolution. He was awarded many significant prizes, including Shaw Prize, Gruber Cosmology Prize , Gold Medal of the Royal Astronomical Society and etc.