How does the Intracluster Medium (ICM) aid in detecting galaxy clusters?

It radiates strongly in X-rays due to its high temperature

The Intracluster Medium (ICM) is a distinctive component of galaxy clusters, consisting of superheated plasma or ionized gas that permeates the space between the constituent galaxies. Because this gas is heated to tens of millions of degrees Celsius by the cluster's immense gravity and dynamical activity (especially during mergers), it becomes highly energetic and radiates intensely across the electromagnetic spectrum, most notably in X-rays. This strong X-ray glow is one of the primary observational signatures astronomers use to locate, map, and study these massive structures, allowing instruments like the Chandra X-ray Observatory to detect the faint emission emanating from the cluster's center.