2024/06/28 by Rahul Ramesh, Ramesh, Rahul, Dylan Nelson +5 · 1 citation
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysics and Cosmic Phenomena #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2407.00172
openalex publication_date 2024/06/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We use the GIBLE suite of cosmological zoom-in simulations of Milky Way-like galaxies with additional super-Lagrangian refinement in the circumgalactic medium (CGM) to quantify the origin and evolution of CGM cold gas clouds. The origin of z = 0 clouds can be traced back to recent (\lesssim 2 Gyr) outflows from the central galaxy (∼ 45 %), condensation out of the hot phase of the CGM in the same time frame (∼ 45 %), and to a lesser degree to satellite galaxies (\lesssim 5 %). We find that in-situ condensation results from rapid cooling around local over-densities primarily seeded by the dissolution of the previous generation of clouds into the hot halo. About \lesssim 10 % of the cloud population is long lived, with their progenitors having already assembled ∼ 2 Gyr ago. Collective cloud-cloud dynamics are crucial to their evolution, with coalescence and fragmentation events occurring frequently (\gtrsim 20 Gyr-1). These interactions are modulated by non-vanishing pressure imbalances between clouds and their interface layers. The gas content of clouds is in a constant state of flux, with clouds and their surroundings exchanging mass at a rate of \mbox\gtrsim 103 M_\odot Myr-1, depending on cloud relative velocity and interface vorticity. Furthermore, we find that a net magnetic tension force acting against the density gradient is capable of inhibiting cloud-background mixing. Our results show that capturing the distinct origins of cool CGM clouds, together with their physical evolution, requires high-resolution, cosmological galaxy formation simulations with both stellar and supermassive black hole feedback-driven outflows.