The non-thermal physics of cosmic rays and magnetic fields in galaxy formation and evolution
Notoriously difficult to constrain with observations and physically intricate to model in simulations, the non-thermal physics of cosmic rays (CRs) and magnetic fields (B-fields), and their effects on galaxies, remain mostly elusive. The study of these processes is timely and scientifically exigent. Current simulations are able to evolve CRs with magnetic fields in tandem with feedback from stars, black holes (AGNs), and other fluid microphysics (e.g., thermal conduction, viscosity). However, one of the key emergent parameters of CR transport, the diffusivity, still remains largely unconstrained. In this talk, I will review our current understanding of the physics of CRs and B-fields and pre-existing observational constraints, and then discuss recent results from the state-of-the-art Feedback in Realistic Environments (FIRE) zoom-in galaxy simulations on showing the impact of CRs on galaxies and CGM gas. Next, I will discuss how observational constraints such as ion absorption columns, X-ray emission, and the tSZ effect can be used to place constraints on their transport models. I will reinforce the importance of including such non-thermal processes in our galaxy formation recipes and propose future studies for further constraining the models.
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