A search for Dark Matter in the centre of the Earth with the IceCube neutrino detector.

Abstract

Understanding the nature of dark matter is one of the major challenges in modern physics. Many effects caused by this mysterious matter have been seen, but until today, there is no clear idea on what this dark matter is made of. The current best model to describe our Universe, the Lambda Cold Dark Matter model, incorporates a dark matter component, which makes up about 27% of all the energy in the Universe and roughly 80% of all the matter. In the most popular models, the dark matter consists of particles which are stable, slowly moving (cold), heavy and only interact weakly and gravitationally with ordinary baryonic matter. These particles are therefore called Weakly Interacting Massive Particles (WIMPs). An excellent candidate for the WIMP is the hypothetical neutralino, the Lightest Supersymmetric Particle (LSP), arising in supersymmetric theories beyond the Standard Model of particle physics. Heavy celestial bodies, such as the Earth, could capture these WIMPs and accumulate them. Over time the WIMPs will self-annihilate and may produce standard model particles, including neutrinos. The dark matter annihilation rate in the center of the Earth, and thus the resulting neutrino flux depend on the local Dark Matter density and the mass of the Dark Matter particle. The neutrino flux could be within reach of a large scale neutrino telescope like the cubic kilometer IceCube Neutrino Observatory located at the South Pole. IceCube would indirectly observe the presence of Earth WIMPs as an excess of neutrinos from the center of the Earth. In this thesis, the first search for Earth WIMPs with the IceCube detector is presented. No significant excess from the direction of the center of the Earth has been found in one year of IceCube data. As a result, upper-limits have been set on the annihilation rate of the WIMPs, the muon flux caused by Earth WIMP-induced neutrinos and the spin-independent component of the WIMP-nucleon cross-section. The obtained upperlimits are the current best limits on the annihilation rate of Earth WIMPs and on the muon flux caused by Earth WIMP-induced neutrinos.