Speaker
Description
The new generation of radio telescopes has unveiled a rich structure of non-thermal radio emissions in galaxy clusters. Among these, radio relics and radio halos stand out as the primary sources, attributed to the synchrotron radiation of relativistic electrons. These structures provide unique insights into in-situ particle acceleration mechanisms and the large-scale magnetic field structure.
Similarly, diffuse gamma-ray emission related to hadronic interactions of cosmic-ray (CR) protons with the intracluster medium (ICM) and its non-detection with current observatories offer strong constraints for simulators. CRs are accelerated through both small-scale astrophysical sources, such as supernova remnants and AGN, and large-scale processes like merger-driven shocks and ICM turbulence. However, none of these acceleration mechanisms can be directly resolved in cosmological simulations. Therefore, subgrid descriptions for cosmic-ray production based on our current knowledge of the underlying kinetic plasma processes are essential to understand the contributions of different sources to the total CR population in a cluster.
For the first time, we implement physically motivated source spectra for both CR protons and electrons in the cosmological TreePM-SPH code OpenGadget3. We run zoom-in simulations of galaxy clusters, where the CR spectra are injected by coupling them to models for stellar and AGN feedback and then evolved via the on-the-fly spectral cosmic-ray solver CRESCENDO. Last but not least, the non-thermal radio and gamma-ray emissions can be directly inferred from the spectra of the cosmic ray population and compared with observational data.
