Optical studies tell us about the physical properties and dynamics of the galaxies in clusters. In particular we are investigating the relationships between the giant central-cluster galaxies and their host clusters. Here is an optical picture of the central-cluster galaxy in the Perseus cluster:
The intracluster medium and dark matter components are best-studied in the X-ray waveband. Below is an X-ray picture of the the Perseus cluster of galaxies. (The circle with radial lines is due to shadowing of the X-rays by the ROSAT PSPC detector-window support.)
Click to return to the start of the clusters section.