My research focusses on the theoretical and numerical studies of the multi-phase interstallar medium (ISM). The computations range from the onset and composition of galactic outflows on kpc scale over the chemical evolution in the disc and the formation of molecular clouds down to cold and self-gravitating regions on sub-parsec scales. Besides a chemical evolution and megnetic fields I focus on the dynamcial impact of cosmic rays in the ISM. My projects can be split into different groups.
Cosmic rays in the interstellar medium
Cosmic rays (CRs) are charged high energy particles that have comparable energy densities in the ISM as the magnetic and kinetic one. Due to their relaltivistic nature CRs have relatively complicated transport and coupling properties. I use numerical simulations with two fluid components to investigate how CRs change the structures in the interstellar medium and drive outflows. The video shows MHD-CR simulations of the supernova-driven ISM with different energy injection types. The left panel shows a simulation with purely thermal energy injection for the SNe. The middle panel uses only CR energy injection and the right panel the combined effect of thermal and CR energy injection.
other video formats avi (49MB), mov (2.5MB)
SILCC: SImulating the LifeCycle of molecular Clouds
Within the SILCC project we numerically investigate the formation process of molecular clouds, their chemcial and magnetic structure as well as their destruction in the SN-driven interstellar medium. We use hydrodynmical simulations of stratified boxes for our studies including a chemical network that follows the abundances of ionised, atomic and molecular hydrogen. The video shows the cuts through the centre of the box for the density and the temperature (left two panels) as well as projections of the density (total, ionised hydrogen, atomic hydrogen, molecular hydrogen and CO)
other video formats avi (44MB), mov (8MB)
Turbulent self-gravitating gas
The coldest and densest condensations in the ISM are star-forming regions which mark the border line between molecular clouds that are supported by thermal pressure and turbulent motions and strongly self-gravitating clumps.
Statistical descriptions of turbulence
The complexity of turbulent motions requires simplifications in the models to understand the origin of statistical properties like the energy transfer between different scales and the composition of turbulent modes. I therefore also study simulations of isothermal driven turbulence in periodic boxes. The video below shows the projected density structures of compressively driven turbulence on the left and solinoidally driven turbulence on the right for a supersonic flow with Mach number 8.
other video formats avi (13MB), mov (1.4MB)