Hidden in plain sight Searching for dark matter signals in the galactic halo

Observations on astrophysical and cosmological scales have provided gravitational evidence of dark matter. Based on these observations, 85% of all the matter in the Universe consists of dark matter, which is often explained by a new particle. Meanwhile, no conclusive detection has yet been made, and its nature is unknown.
In this thesis, astrophysical observations from within the Galactic halo are used to explore various dark matter candidates.
Dark matter particles can decay or annihilate into standard model particles and are observable through these secondary particles from regions in the sky with a high dark matter density. As the Milky Way is embedded in a dark matter halo, it offers the highest observable flux on Earth.
We used current and future high-energy neutrino observations to test dark matter properties with a dark matter mass in the GeV to PeV energy range.
Moreover, we present the sensitivity of a near-future X-ray survey to detect the well-motivated dark matter candidates sterile neutrinos and axion-like particles that have dark matter masses in the keV energy range.
Finally, in the last chapter, we use the abundance of Milky Way satellite galaxies to distinguish between particles that have light (keV) and heavy (>GeV) masses. We developed an analytical model to predict the abundance of satellite galaxies for a given dark matter model, and exclude those that do not represent the observations.