Groups & Clusters of GalaxiesAnother intriguing question is the ultimate fate of the colossal gas reservoirs in galaxy clusters. The crush of all the gas and dark matter in the cluster pushes the particles in the center of the cluster closer together. This causes them to collide more frequently and to slowly lose their energy to radiation, like a tire with a slow leak. In a billion years or so, this radiation leak will take its toll and, if there is no energy source to offset the losses, the gas will cool and slowly settle – in what is called a cooling flow – onto a massive galaxy in the center of the cluster.
New observations of galaxy clusters by Chandra and the XMM Newton X-ray Observatory, together with radio observations, may point to a resolution of this problem. They show that in a number of cases, the inflow of cooling gas appears to be deflected by magnetic fields, and perhaps heated by explosions from the vicinity of a supermassive black hole at the core of the central galaxy. Whether or not such violent activity will explain the shortage of cool gas should become clear in the next few years.
Clues to the origin, evolution and destiny of the universe
More: The Coma Cluster and the Virgo Cluster
Revised: January 29, 2008