@misc{9246690,
  abstract     = {{The gaseous halo around galaxies, known as the circumgalactic medium (CGM), has been inferred from observations and simulations to transition from cold chaos to hot stability (virialisation), but the road it takes is uncertain. One of the possible routes is via the ejections of energy and matter from stars, called stellar feedback, within the galaxy, providing the necessary thermal support to stabilise the CGM. In this thesis, the evolution of the CGM was analysed and compared between multiple state-of-the-art simulations provided by the AGORA Collaboration. These simulations varied primarily in their numerical implementation and stellar feedback model. By matching their gas properties, each simulation could be distinguished in their CGM by their unique set of assumptions, and an improved understanding of their respective models and implementations could be gleaned. Each code predicted a CGM baryon mass fraction relative to the cosmic baryon fraction in the range of ∼ 20 − 50%, implying all could regulate and maintain a significant fraction of baryons from their central galaxy in the CGM, albeit with different efficiency. The thermal phases of these baryons varied significantly, where certain codes with strong preventive feedback developed a hot gas dominated CGM early at z ≳ 4, before predicted accretion shocks, while some with instead strong ejective feedback predicted a much later transition at z ≲ 1.5. It was shown that including kinetic feedback, together with thermal, also greatly improved the ability to eject baryons, improving the regulation of the total baryon fraction. An odd commonality between most codes, independent of their numerical implementation or stellar feedback model, was a shared tendency towards halo wide virialisation, at similar times in the outer regions. This does not align with the current standard theories that predict a stronger radial dependence for the virialisation, either stabilising from the inside-out or from the outside in, and therefore has interesting implications for the evolution of the CGM.}},
  author       = {{Lindh, Isak}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Formation of the Circumgalactic Medium in Cosmological Zoom-in Simulations}},
  year         = {{2026}},
}