Galaxy clusters are the largest objects in the universe held together by gravity. They contain enormous amounts of superheated gas, with temperatures of tens of millions of degrees, which glows brightly in X-rays, and can be observed across millions of light years between the galaxies.
Galaxy clusters are the largest objects in the universe held together by gravity. They contain enormous amounts of superheated gas, with temperatures of tens of millions of degrees, which glows brightly in X-rays, and can be observed across millions of light years between the galaxies. This image of the Abell 2744 galaxy cluster combines X-rays from Chandra (diffuse blue emission) with optical light data from Hubble (red, green, and blue).
Image credit:X-ray: NASA/CXC; Optical: NASA/STScI