The Indirect Detection of Non-baryonic Dark Matter

我提议的工作特别旨在识别由当前和未来间接暗物质探测实验提供的宇宙射线反粒子和辐射的高精度光谱中的特征，这些特征不能在传统的天体物理学场景中简单地理解。在我提出的每一个项目中（如下所述），我将对这些光谱应用理论建模和统计分析技术，并推断出特定种类的暗物质粒子的特性限制，这些粒子的湮灭或衰变产物可能导致这些特征。1. “暗物质对星系和星系团周围21cm信号空间分布的影响”在这个项目中，我计划继续研究暗物质对21cm氢发射信号的影响，这是由星系际介质中氢原子从2p超精细能级到1s超精细能级的电子跃迁造成的。在我的研究中，我计算了由弱相互作用大质量粒子（或wimp）或轻暗物质（LDM）湮灭产生的高能粒子的程度，这些粒子被认为构成了环绕星系的暗物质，在承认几代暗物质结构时，在IGM中加热、电离和激发中性氢。我证明了这种相互作用可以显著地改变宇宙的热和电离历史，并计算了它们对全球21cm信号的影响。据推断，对于暗物质结构演化的某些模型，wimp和具有某些特性的LDM对全球21cm信号的影响原则上可以通过当前的无线电干涉仪（如LOFAR）检测到。在我提出的项目中，我将不再关注全球21cm信号，而是关注21cm信号在星系和星系团周围的空间分布，这些星系和星系团将被当前的射电干涉仪（如LOFAR）观测到。暗物质湮灭的产物可以在更大的区域内显著加热和电离周围的氢，这可能使暗物质更容易被探测到。2. “利用FGST间接探测被破坏的暗物质子结构，以及对直接探测的影响”最近来自暗物质晕的高分辨率模拟的结果表明，WIMP暗物质的卫星可能正在穿越银河系。据预测，这些卫星内的WIMP湮灭将产生独特的伽马射线细长剖面，作为卫星的确凿证据。此外，被潮汐力破坏的卫星预计会在它们的尾迹中留下残留的暗物质流。通过太阳附近的流可以显著增强预期在直接探测实验中测量到的年度信号调制。通过使用我开发的理论模型来计算由迁移卫星内的WIMP湮灭引起的伽马射线发射的能谱和空间分布，以及计划于2009年开发的FGST全天伽马射线图的统计分析，我将约束WIMP的特性并对被破坏卫星的寿命进行推断。此外，通过使用卫星轨迹的理论模型和来自直接探测实验（如ZEPLIN-II）的约束，我将推断出卫星遭受质量剥离程度的约束。3. “惰性中微子暗物质的替代产生机制”我最近的研究不赞成通过Dodelson-Widrow机制（DWM）产生的惰性中微子构成目前推断的所有暗物质丰度的设想。利用XMM和钱德拉的新结果，我将研究和推断由DWM替代机制产生的无菌中微子的性质约束。

My proposed work specifically aims at identifying features within the high-precision spectra of cosmic-ray antiparticles and radiation, provided by both current and future indirect dark matter detection experiments, that cannot be simply understood within a conventional astrophysical scenario. In each of my proposed projects (outlined below), I will apply theoretical modelling and statistical analysis techniques to these spectra and infer constraints on the properties of particularly-suited species of dark matter particles whose annihilation or decay products could result in such features. 1. 'The effect of dark matter on the spatial distribution of the 21cm signal surrounding galaxies and clusters' In this project I plan to continue my investigation of the effect of dark matter on the 21cm hydrogen emission signal, resulting from electronic transitions from the 2p to 1s hyperfine levels of hydrogen atoms residing in the intergalactic medium. In my research I calculated the extent to which the energetic particles resulting from the annihilation of weakly interacting massive particles (or WIMPs) or light dark matter (LDM), assumed to constitute the dark matter thought to surround galaxies, heated, ionised and excited neutral hydrogen in the IGM when acknowledging several generations of dark matter structures. I demonstrated that such interactions could significantly alter the thermal and ionization history of the Universe, and calculated their effects on the global 21cm signal. It was deduced that for certain models of the evolution of dark matter structures, the effects on the global 21cm signal by WIMPs and LDM with certain properties could in principle be detectable by current radio-interferometers such as LOFAR. In my proposed project, instead of focusing on the global 21cm signature, I will now focus on the spatial distribution of the 21cm signal specifically around galaxies and clusters that are to be observed by current radio-interferometers such as LOFAR. The products of dark matter annihilations can significantly heat and ionise the surrounding hydrogen throughout a much larger region than if dark matter was absent, potentially making dark matter much easier to detect. 2. 'Indirect detection of disrupted dark matter substructure using FGST, and the implications for direct detection' Recent results from high-resolution simulations of dark matter halos imply that satellites of WIMP dark matter may be traversing through the Milky Way. WIMP annihilations within these satellites are predicted to yield unique elongated profiles of gamma-rays, acting as a smoking gun signature for satellites. Also, satellites disrupted by tidal forces are predicted to leave residual streams of dark matter in their wakes. Streams passing through the solar neighborhood could significantly enhance the annual signal modulation expected to be measured at direct detection experiments. By using the theoretical models that I have developed to calculate the energy spectra and spatial distribution of gamma-ray emissions resulting from WIMP annihilations within migrating satellites, together with a statistical analysis of the FGST all-sky gamma-ray map, scheduled for development in 2009, I will constrain the properties of WIMPs and make inferences on the lifetime of disrupted satellites. In addition, by using theoretical models for the trajectories of satellites and constraints from direct detection experiments, such as ZEPLIN-II, I will deduce constraints on the degree of mass-stripping suffered by satellites. 3. 'Alternative production mechanisms for sterile neutrino dark matter' My recent research disfavours a scenario where sterile neutrinos, generated through the Dodelson-Widrow mechanism (DWM), constitute all of the currently inferred dark matter abundance. Using new results from XMM and Chandra, I will investigate and deduce constraints on the properties of sterile neutrinos generated by mechanisms alternative to the DWM.