Title: Cosmic-ray transport in star-forming galactic disks
Abstract:
In recent years, there has been an increasing interest in the role of cosmic rays (CRs) in galaxy evolution. Most MHD galaxy simulations including CRs have shown that the latter can contribute to the dynamics of the interstellar medium (ISM), aiding in the internal support against gravity and in the launching of galactic outflows. However, the extent to which CRs affect these phenomena is strongly sensitive to the way different CR transport mechanisms are treated in simulations. With the goal of understanding the details of CR transport on galactic scales, we compute the propagation of mildly-relativistic CRs in different galactic environments typical of nearby disk galaxies reproduced by the TIGRESS MHD simulations. We consider the realistic scenario in which resonant Alfvén waves are responsible for CR scattering, with a scattering coefficient that varies with the properties of the background gas. I will review the main results of this analysis, and discuss the impact of CRs on the dynamical state of the ISM, with a particular focus on the contribution of CRs to driving galactic outflows.
