Exploring streaming cosmic ray propagation in zoom-in molecular cloud simulations

Cosmic rays are charged, relativistic particles that pervade the galaxy at similar total energy densities as the magnetic fields and even the kinetic turbulent energies. The most common in number density are the GeV cosmic rays, which are subject to resonant instabilities with the magnetic fields embedded in the medium that they are propagating through. The net effect of the instability is to determine the dynamics of the distribution function, making populations of relativistic particles drift at the local ion Alfven speed. This tightly couples the distribution function to the dynamical timescales of the magnetic field, and subjects the particles to the structure and statistics that govern the ion Alfven fluctuations (the ionization state, the gas density, and the magnetic field). In this project we will explore how streaming GeV particles are transported through a host of different zoom-in simulations of molecular clouds. We will use the recently developed criptic code for doing post-processed cosmic ray transport, detailed in Krumholz et al. (2022), coupled with molecular cloud simulation data from global galaxy simulations detailed in Hu et al. (2023). We will investigate how the diverse morphology of the magnetic fields and ionization state of the gas in these systems gives rise to different diffusion coefficients, which can be compared directly with observations.