Theoretical astroparticle physics
Astroparticle physics is a cross-disciplinary research area at the interface of particle physics, astrophysics and cosmology. Key questions in astroparticle physics are:
  • What is the Universe made of? In particular: What is dark matter?
  • What are the properties of neutrinos? What is their role in cosmology and astrophysics?
  • What will gravitational waves tell us about violent cosmic processes and about the nature of gravity?
  • What is the origin of cosmic rays?
  • Do protons have a finite life time?
An answer to any of these questions would mark a major break-through in understanding the Universe and would open an entirely new field of research on its own (ASPERA - the European roadmap for astroparticle physics).
Dark matter distribution
Figure: Three-dimensional distribution of dark matter in the Universe obtained by the Hubble space telescope through the observation of microlensing events. Credit: NASA, ESA.

Currently our research in astroparticle physics mainly focuses on dark matter. Dark matter is an invisible and unidentified fluid that makes up about five-sixths of all matter in the Universe. Dark matter alters the motion of stars and galaxies, bends the light emitted by distant luminous sources, and allows for the formation of all cosmological structures we see in the Universe. Yet, the particles forming dark matter have so far escaped detection, and even their basic properties remain unknown.

In the field of dark matter, we strive to understand:

  • What are the fundamental interactions of dark matter?
  • Can we detect dark matter particles via scattering by target nuclei?
  • Can we devise new and more effective strategies for dark matter detection?
  • Can dark matter be produced at particle accelerators?
  • How is dark matter distributed in the Milky Way?
  • Can we explain why today dark matter is five times more abundant than ordinary matter?
  • The tools of our research in astroparticle physics are quantum field theory, non-relativistic effective theories, general relativity, galactic dynamics, computational methods, and Bayesian statistics.

    Our research is performed within a truly multi-disciplinary scientific environment which developed across traditional departmental boundaries.

    Dark matter collision
    Figure: Dark matter particle collision with a Xenon atom as it could be detected by the LZ experiment. Credit: SLAC National Accelerator Laboratory.