TY  - GEN
TI  - Cosmic ray feedback in galaxy formation and a numerical model for turbulence
N2  - Feedback processes play an important role in galaxy formation since they regulate star formation both in low mass galaxies and in massive galaxy clusters. Which mechanisms dominate and how the feedback couples to the surrounding medium, are still open questions. In this thesis, we study the feedback from cosmic rays in different environments in more detail. We develop steady state models for a sample of galaxy clusters, in which cosmic ray heating together with thermal conduction prevents large cooling flows. Observational constraints reveal that cosmic ray heating is only viable in clusters that do not show signatures of enhanced cooling. This might indicate a self-regulated feedback cycle. On galactic scales, cosmic rays can drive winds if they are allowed to diffuse or stream out of the galaxy. We demonstrate in simulations of isolated galaxies that cosmic rays are able to regulate star formation in low mass galaxies but the wind efficiency drops rapidly with increasing galaxy mass. Furthermore, almost all astrophysical flows are highly turbulent. This is a challenge for numerical simulations, which cannot resolve all scales of the turbulent cascade. Therefore, we implement a model for turbulence on subgrid scales into the hydrodynamics code AREPO. We validate our model in idealized test cases and apply it to simulations of turbulent boxes.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/25527/
A1  - Jacob, Svenja
Y1  - 2018///
KW  - Cosmic rays
KW  -  Galaxy formation
KW  -  Galaxy clusters
KW  -  Galactic winds
KW  -  Turbulence
ID  - heidok25527
AV  - public
ER  -