Special Session SS15  3 July 2024

The hot phase of the circum-galactic medium (hot CGM)

Aims and scope

The interactions between gas and galaxies are of paramount importance to our understanding of structure formation. The galactic baryon cycle takes place in the immediate surroundings of galaxies, named the circumgalactic medium (CGM). More than a decade of deep spectroscopic surveys of galaxies, absorption line studies in quasar spectra and sophisticated numerical simulations have placed interactions between galaxies and the CGM at the center of our quest to understand the formation of galaxies and the growth of the cosmic web. However, until very recently, the hot phase of the CGM was the least known of the gas phases surrounding galaxies despite being most likely the dominant share of CGM gas by mass.

The goal of the session is to establish new inter-disciplinary, multi-wavelength collaborations to build a better understanding of the physics of the hot phase of the CGM and its role in holistic views of galaxy formation and evolution. We will discuss new X-ray and SZ observational advances on the hot phase of the CGM in our Milky Way, nearby galaxies and in the general galaxy population and how they relate to other phases of the CGM. We will then discuss the implication of these observations in the multi-phase CGM paradigm and in the light of current and upcoming hydrodynamical cosmological simulations.


  • X-ray observations
  • SZ observations
  • Theoretical advances, numerical simulations and the multi-phase CGM paradigm

Invited speakers

  • Sanskriti Das (Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, US)
  • Dylan Nelson (Center for Astrophysics of Heidelberg University, Germany)
  • Yi Zhang (Max-Planck Institute for extraterrestrial Physics, Garching, Germany)
  • John Zuhone (Center for Astrophysics, Harvard & Smithsonian, Cambridge, US)

Scientific organisers

Johan Comparat (M, MPE, Germany), Annalisa Pillepich (W, MPIA, Germany), Celine Peroux (W, ESO, Germany), Gabriele Ponti (M, INAF, Italy), Paola Popesso (W, ESO, Germany), Andrea Merloni (M, MPE, Germany), Freeke van de Voort (W, Cardiff University, UK), Ian McCarthy (M, LJMU, Liverpool, UK)


Updated on Tue Feb 13 19:15:42 CET 2024