My group at the HITS closely collaborates with the research institutes of the Center for Astronomy at Heidelberg University (ZAH, these are ITA, ARI, LSW), as well as with the Max-Planck-Institute for Astronomy. We also participate in the Heidelberg International Max-Planck Research School (IMPRS) for Astronomy & Cosmic Physics at Heidelberg University.
- Galaxy formation
Galaxy formation is the central subject of my research. Here the physics involved is an incredibly complicated blend of gravity, hydrodynamics, nuclear and atomic physics, as well as magnetohydrodynamics and radiation physics. The fundamental equations governing the forces between particles and fields in this low-energy regime are all well established, yet we are far from understanding how they produce the bewildering complexity of cosmic objects we see around us, like galaxies, globular star clusters, compact objects, or damped Lyman-alpha absorbers in the intergalactic medium, to name just a few. My goal is to make progress in untangling these physical processes, to separate the important from the unimportant, and to find some answers to the many questions that astrophysicists face in contemporary extragalactic astronomy.
- Numerical cosmology
I make extensive use of simulation techniques to study cosmic structure formation, both based on collisionless and hydrodynamic simulations. In order to allow use of the full power of modern supercomputers, I develop massive parallel simulation algorithms for distributed memory computers, and study new methods for discretizing the Euler and Navier-Stokes equations, for example on a moving mesh. One important goal is to develop new calculational tools that allow multi-physics, multi-scale simulations on peta-scale supercomputers.
- Dark matter and dark energy
Through numerical N-body simulations I seek clues to the nature of the dark matter and aim at advancing strategies for exploring the formation of our Galaxy, for searching for signals from dark matter annihilation, and for designing experiments for direct detection of dark matter. Dark energy has emerged as one of the most important challenges for modern field theory and cosmology. The evidence for an accelerated expansion history of the universe is by now quite compelling, but the magnitude of the implied dark energy component cannot be naturally explained as a vacuum energy, in addition to raising a new coincidence problem: Why is the dark energy dominating just now? I work on carrying out high-resolution cosmological simulations of different dark energy cosmologies, including also non-standard theories of gravity and coupled dark matter-dark energy cosmologies, and to compare them to the standard ΛCDM model. The goal is to explore the viability of these theories and to inform strategies for successfully constraining dark energy through observations.
TEACHING / NEXT LECTURE
The next time I teach “Fundamentals of Simulation Methods” (MVComp1) will be in the winter semester 2015/16 at Heidelberg University.