Intracluster medium

In astronomy, the intracluster medium (ICM) is a superheated (very hot) plasma that spreads through a galaxy cluster. The gas is mostly ionized hydrogen and helium, which makes up most of the baryonic material in the clusters. The ICM is heated to 10 to 100 million kelvins and gives off strong X-ray radiation.

Image of the intracluster medium in the Perseus Cluster taken by the Chandra X-ray Observatory

Composition

The ICM is mainly made of normal baryons, ionized hydrogen and helium.^[1] This plasma contains heavier elements, including iron.