Theory Seminar

A stress test of Galactic cosmic rays

by Philipp Mertsch (RWTH Aachen)

Wegelerstraße 10/2-2.019 - Seminar Room BCTP I (PI)

Wegelerstraße 10/2-2.019 - Seminar Room BCTP I



The Galaxy is pervaded by a flux of high-energy, non-thermal particles: cosmic rays.
The last years have seen great progress towards elucidating the century-old questions of cosmic ray origin. Yet, a number of anomalies point to more complex dynamics than previously thought. With new and upcoming data, we are in a position to put some stress on the standard picture of cosmic rays and address some of the fundamental questions: What is the energy of transition from Galactic to extra-Galactic sources? How is magnetised turbulence shaping the spectra and anisotropies of cosmic rays? And what is the feedback of cosmic rays on their environments? 

In this talk, I will describe some of our recent works in that direction. Diffuse emission in high-energy gamma-rays and neutrinos, as measured by experiments like IceCube at the South Pole, is a great tool for studying cosmic rays elsewhere in the Galaxy. 
We have recently provided new predictions for gamma-rays and neutrinos, including properly evaluated model uncertainties. I will address the need for better gas maps and explain how we used Bayesian inference in producing the highest resolution 3D maps of atomic and molecular hydrogen in the Galaxy to date. Finally, I will also discuss our attempts at clarifying the origin of the puzzling small-scale anisotropies of cosmic rays and advertise those as a means to get better constraints on the nature of magnetised turbulence.