As hints of physics beyond the standard model become the major driving force behind future large-scale projects, it is increasingly important to consider all sources of evidence and constraints. Here, I illustrate the importance of considering the connection between particle physics, cosmology and astrophysics, mainly via two examples: 1) the sterile neutrino and its impact on cosmology, and 2) the 511 keV line from electron-positron annihilation in the galactic centre.