KIPAC Seminar: Cosmic rays in cosmological simulations - bridging scales

Abstract: Galaxy clusters and their role in the large-scale structure of the Universe, the cosmic web, have been studied extensively through observations and simulations. However, many of the high-energy process that take place in these structures still elude observations and pose significant challenges for simulations of large-scale structure formation. Most notably, the accretion of matter onto the cosmic web and the collisions of galaxy clusters embedded in it dissipate a large fraction of their gravitational energy in the form of shocks. These shocks heat the intra-cluster medium to keV energies and can accelerate protons and electrons to relativistic velocities. Non-thermal emission from relativistic electrons gives insight into the strength and morphology of intra-cluster magnetic fields, as well as providing powerful tracers of structure formation shocks. Large-scale simulations which include the effects of CRs have been difficult to achieve since the difference between the scale where CRs interact with the thermal gas and the resolution of these simulations spans more than 20 orders of magnitude.PIC and hybrid simulations are the most successful tools to study cosmic ray acceleration at astrophysical shocks. However, most of these simulations are limited to 1D/2D due to computational constraints. In this talk, I will give an overview of how we work to improve the modeling of CRs in large-scale simulations of cosmological structure formation. I will introduce the spectral CR model we use to evolve CR populations on-the-fly in our simulations and its application to simulations of the local Universe and will give an outlook on improvements to the PIC code entity which we use for 3D PIC simulations of ICM shocks.