Project Description
More than 100 years after the discovery of cosmic rays, a complete understanding of their origin is still out of reach. Some progress has been made, identifying the low-energy component (up to the so-called cosmic-ray knee, i.e. up to \(10^{15}\) eV) as coming from within the Milky Way, and the highest-energy part (above the so-called cosmic-ray ankle, i.e., energies above \(10^{18.5}\) eV) as being of extragalactic nature. However, very little is known about the transition region between the knee and the ankle. Combining observations with theoretical models makes it clear that these two standard components are insufficient to describe observational data. An additional population, filling up the gap between Galactic and extragalactic standard contribution, was suggested, named Component B.During Phase 1 we investigated the role of the Galactic wind termination shock (GWTS) in the acceleration of particles contributing to cosmic-ray flux in this intermediate region, and how it fits into the global picture of the cosmic-ray flux in the region of interest.
In Phase 2 we will focus on superbubbles, which have been suggested to reach super PeV energies, and local outflows potentially driven by the superbubbles themselves, addressing the three questions:
- Are superbubbles or any of their constituents able to accelerate CRs to significantly contribute to the CR flux in the transition region?
- Which time and space dependent signatures of neutral messengers can be expected from superbubbles?
- To what extent do conventional Galactic and extragalactic sources and the Component B (superbubbles, local outflows, the GWTS) contribute to the transition region?
