Intergalactic medium
Intergalactic medium is the diffuse matter that exists in the space between galaxies. It consists primarily of ionized hydrogen and traces of heavier elements.
The intergalactic medium is discussed in astrophysics, cosmology, and large-scale structure studies.
Status
The intergalactic medium is studied through absorption features in the spectra of distant sources and through cosmological simulations. Models address its composition, temperature distribution, and role in galaxy formation and evolution.