The Indirect Detection of Non-baryonic Dark Matter

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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.