Fernando Hidalgo Pineda: What Goes Around Comes Around: Life and Death of Cold Gas in the Baryon Cycle

The baryon cycle is a cornerstone of galaxy evolution, yet its multiphase nature remains poorly understood. Cold gas appears in galactic outflows, ram-pressure stripped tails, and infalling high-velocity clouds, surviving transport through hot plasmas across tens to hundreds of kiloparsecs. This presents a long-standing challenge: classical cloud-crushing theory predicts rapid destruction via hydrodynamic instabilities, while observations reveal abundant cold gas throughout the ISM, CGM, and ICM. Most models rely on isolated, spherical clouds in idealised settings, neglecting the fractal, magnetised, and turbulent nature of real media. This leaves open how cold gas survives acceleration in winds, infalls through stratified halos, and fuels star formation in cluster cores. In this talk, I present new theoretical and numerical results addressing the full lifecycle of multiphase gas, from formation in fractal, magnetised ISM to transport through the CGM and ICM. I demonstrate a generalised survival criterion that replaces isolated clouds with realistic ISM morphologies, showing how magnetic fields and effective cold-phase depth determine whether cooling dominates over mixing. I then trace the evolution of this gas through turbulent, stratified environments, demonstrating how cooling, turbulence, and gravity shape the morphology, kinematics, and distribution of cold structures. These results offer new insights into HVCs, precipitation-driven star formation, and cold-gas budgets in galactic haloes, with direct implications for the evolution of galaxies.