MeV暗物质与小尺度结构
MeV Dark Matter and Small Scale Structure
摘要：
具有电弱标度质量的WIMP（中性伴子等）保持与其他粒子种类的动力学平衡，直到温度大约在10 MeV至1 GeV的范围内，导致形成质量小至$10^{-4} M_{\odot}$至$10^{-12} M_{\odot}$的暗物质亚结构。然而，如果暗物质由MeV量级的粒子组成，就像银河系隆起511 keV辐射的观测所激发的那样，这样的粒子自然会与宇宙中微子背景保持动力学平衡，直到相当晚的时候。这将导致对质量低于约$10^7 M_{\odot}$至$10^4 M_{\odot}$的小尺度结构的强烈抑制。这个截止尺度对现在和未来寻找微弱的本星系群卫星星系和寻找失踪的卫星星系具有重要意义。
英文摘要：
WIMPs with electroweak scale masses (neutralinos, etc.) remain in kinetic equilibrium with other particle species until temperatures approximately in the range of 10 MeV to 1 GeV, leading to the formation of dark matter substructure with masses as small as $10^{-4} M_{\odot}$ to $10^{-12} M_{\odot}$. However, if dark matter consists of particles with MeV scale masses, as motivated by the observation of 511 keV emission from the Galactic Bulge, such particles are naturally expected to remain in kinetic equilibrium with the cosmic neutrino background until considerably later times. This would lead to a strong suppression of small scale structure with masses below about $10^7 M_{\odot}$ to $10^4 M_{\odot}$. This cutoff scale has important implications for present and future searches for faint Local Group satellite galaxies and for the missing satellites problem.
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