Speaker
Description
The circumgalactic medium (CGM) is the nexus of galaxy formation. Fresh gas that fuels star formation must pass through the CGM to reach the interstellar medium, while material accelerated by feedback and expelled from galaxies builds up a gaseous reservoir in the CGM. Observations reveal vast amounts of cold gas in the CGM, yet the processes that shape its dynamics remain uncertain. Condensation powered by the thermal instability is able to generate cold gas clouds in situ but can be offset by feedback processes. Cosmic rays (CRs), a key component of non-thermal galactic feedback, impact cold gas clouds by heating and exerting pressure, which can slow the inevitable condensation process. We present the results of a dedicated simulation set that tries to shed light on the role of CRs in the formation and the life of cold gas clouds in the CGM. We show that the impact of CRs on the thermal instability highly depends on the details of CR transport and highlight that fast CR transport allows for a quick escape of CRs from forming cold clouds, diminishing their stabilizing effect, and allowing clouds to collapse more readily. Furthermore, we also emphasize the importance of high numerical resolution in studying the interactions of CRs and the multiphase CGM by demonstrating that insufficiently resolved simulations exaggerate CR–mediated effects.
