Abell 1795: A Galaxy Cluster's Cooling Flow

Explanation: Throughout the Universe , galaxies tend to swarm in groups ranging from just a handful of members to casts of thousands. Astronomers have realized since the early 1970s that the larger swarms, immense clusters of galaxies millions of light-years across, are immersed within tenuous clouds of hot gas which glow strongly in x-rays. These clouds may have been heated by their collapse in the early Universe, but in many galaxy clusters , the gas appears to be cooling. This Chandra Observatory x-ray image reveals a striking cooling flow in the central regions of the galaxy cluster cataloged as Abell 1795. Brighter pixels in the false-color image represent higher x-ray intensities. The bright filament down the center indicates gas condensing and cooling -- rapidly loosing energy by radiating x-rays. At the very top of the filament is a large, x-ray bright galaxy. As it moved through the cluster gas cloud, the massive galaxy's gravitational influence seems to have created this cosmic wake of denser, cooling gas . Continuing to cool, the cluster gas will ultimately provide raw material to form future generations of stars.