Galactic Gas Distribution and Cosmic-Ray Transport

While space between the stars is transparent to the naked eye, it is hardly empty. It is filled with a very dilute gas, radiation, magnetic fields, and high-energy particles, so-called cosmic- rays. All these constituents interact with each other forming a highly dynamical environment. In this project we will try to improve our understanding of this environment, where we focus on the cosmic rays and the gas. The gas in the interstellar medium can be studied by dedicated observation of different spectral lines. Since we observe this gas from within the Milky way it is, however, very hard to determine its three-dimensional spatial distribution. The only directional information from the observations is the angular distribution of the emission and a shift of the spectral lines that can be translated to a relative motion between gas and observer. In this project, we therefore aim to compute new three-dimensional distributions not only of the gas, but also of cosmic-rays, their sources and other relevant quantities. For this, we will apply so-called information field theory models, which can relate observations to a model of the three-dimensional distribution in a statistical fashion and produce a best fit model in the process. We will utilize current knowledge on the interaction between the gas and the cosmic rays to obtain a joined model for the three -dimensional distribution of all these constituents. For this we combine modern codes for information field theory and for cosmic- ray transport to produce a joined inference framework. This will be an important advancement both in information field theory and in our understanding of the interstellar medium.