Astrolunch: Christoph Pfrommer

Tue, 17/08/202112:30-13:30
Title: Cosmic Rays in Galaxy Formation: Acceleration, Transport, and Feedback
Abstract:  Understanding the physics of galaxy formation is an outstanding problem in modern astrophysics. Recent cosmological simulations have demonstrated that feedback by star formation, supernovae and active galactic nuclei appears to be critical in obtaining realistic disk galaxies and to slow down star formation to the small observed rates. However the particular physical processes underlying these feedback processes still remain elusive. In particular, these simulations neglected magnetic fields and relativistic particle populations (so-called cosmic rays). Those are known to provide a pressure support comparable to the thermal gas in our Galaxy and couple dynamically and thermally to the gas, which seriously questions their neglect. After introducing the underlying physical concepts, I will present our recent efforts to model cosmic ray physics and magnetic fields in galaxy formation. In particular, I will review cosmic ray acceleration at supernova remnants, how cosmic rays interact with the magnetized interstellar medium and propagate through galaxies. Finally, I will demonstrate that cosmic rays play a decisive role in the formation and evolution of spiral galaxies by providing feedback that regulates star formation and drives gas out in form of galactic winds. In this process cosmic rays pressurize galactic halos, which modifies the cosmic accretion of priordial gas, the thermodynamic structure of the circumgalactic medium, and stellar and gaseous disk sizes. This argues that a complete understanding of galaxy formation necessarily includes these non-thermal components
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Meeting ID: 847 4056 5269
Passcode: w31c0m3