Voids
Intergalactic clouds
Extragalactic astronomy
Astrophysical dust processes
Intergalactic filaments
Quasar absorption line spectroscopy
Intergalactic gas
Dark matter
Missing mass
Intergalactic medium phases
Intergalactic matter
IGM
Intracluster medium
The matter or environment between the galaxies of a cluster.
Intergalactic medium