Speaker
Description
Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of the Milky Way and nearby galaxies and are thought to play an essential role in governing their evolution. However, many of their properties remain poorly constrained. Since direct measurements of CRs are limited to our local environment, observations of radio and gamma-ray emission arising from CRs provide a powerful tool to constrain their transport properties and interactions with the ISM and magnetic fields in other galaxies. To better understand the link between observational signatures and CR physics, we use a series of magneto-hydrodynamical simulations with AREPO that include self-consistent CR physics, complemented by post-processing to model CR spectra and their multi-frequency emission. These simulations have enabled us to identify the processes required to simultaneously reproduce observed correlations and spectra of star-forming galaxies in the radio and gamma-ray regimes. Building on this, I will show first results of applying this framework to cosmological zoom simulations within the Auriga galaxy formation model, targeting dwarf to Milky Way-sized galaxies and their satellites to explore how environmental factors — such as magnetic field strengths and host interactions — impact CR-related observables. In particular, I will assess how well the commonly used relation between the gamma-ray emission and star formation rate of galaxies can help us to constrain CR transport parameters at the low-mass end, which has important consequences on constraining CR feedback and its implications for galaxy evolution. Additionally, by incorporating more detailed modelling of CR electrons and tracking their spectral evolution in time, I will assess the validity of the steady-state assumption commonly used in interpreting radio and gamma-ray observations. This will allow us to evaluate how these assumptions influence our understanding of the underlying CR physics and magnetic field properties and provide an invaluable link between theory and observations.
