Understanding Galactic Cosmic Rays in the Local Bubble and beyond.

Cosmic rays are charged particles that have been accelerated to high energies throughout the universe. This project aims to explain a feature in the spectrum of observed cosmic ray energies through a mechanism driven by passing stars or supernova remnants in a nearby region of the Milky Way. The team will perform computer simulations to test if this explanation can reproduce the observed feature and predict other observable features.

The team will also incorporate their research into the UCSD STARS (Summer Training Academy for Research Success) program. This award advances the goals of the Windows on the Universe Big Idea.

The project will use a combination of analytical and numerical simulations of the re-acceleration of cosmic rays by weak shocks in the Local Bubble. These simulations will model the injection, transport, angular structure, and chemical composition of cosmic rays that have been re-accelerated by the shocks and then transported to the earth through magnetic flux tubes.

The results will be compared with observations to determine whether this scenario can successfully explain the properties of the bump in the cosmic ray spectrum at intermediate energies. The work will be incorporated into a summer program at UCSD STARS and will also support the mentorship of a student from an underserved community in the San Diego area.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.