RUB Research School

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Author
Name Aerdker, Sophie
Research field Astrophysics
Career stage doctoral researcher
Home university/institution Ruhr-Universität Bochum (RUB)
Department/Research unit at home university/institution Physics and Astronomy
Chair/Working group at home institution Institute of Theoretical Physics IV

International activity
Country United States
Location Madison, Wisconsin
University UW Madison
Fund Research School PR.INT
Type of activity research stay
Period starts 02-04-2024
ends 30-06-2024
Keywords Astrophysics, cosmic rays, turbulent magnetic field, particle transport, acceleration
Report
I visited Prof. Dr. Ellen Zweibel's group at UW Madison to work on cosmic ray transport and acceleration in our Galaxy.

Cosmic Rays (CRs) are high-energy particles, mostly protons, that are traveling nearly with the speed of light. CRs are one source of natural radiation and were discovered by Victor Hess in balloon experiments in 1912. Today, they are observed with the help of satellites as well as earth-based telescopes.

We know that CRs originate from space and gain energy by acceleration. The energy distribution of CRs we observe at Earth is a power-law: Most CRs gain few energy, few CRs gain a lot of energy, which indicates stochastic acceleration mechanisms. We also know that most of the CRs up to a certain energy originate from the Sun and those of higher energies from our Galaxy, likely being accelerated at Supernova Remnants (SNRs) resulting from the explosion at the end of a star's lifetime. CRs of the highest energies measured must originate from distant galaxies.

The exact sources and acceleration mechanisms of high-energy CRs, however, are still unclear. Of particular interest is the region in the energy spectrum where the transition from Galactic to extra-galactic origin is occurring.

At UW Madison we worked on time-dependent Galactic wind structures and cosmic ray transport and acceleration in turbulent magnetic fields. For that, we used different computational frameworks like Athena++ for simulating time-dependent wind structures and CRPropa3.2 for test particle transport and acceleration.


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