These four galaxy clusters were part of a large survey of over 300 clusters used to investigate shaded energy,the mysterious energy that is currently driving the accelerating expansion of the Universe, as described in our latest press release. In these composite images, and X-rays from NASA's Chandra X-ray Observatory (purple) gain been combined with optical light from the Hubble Space Telescope and Sloan Digital Sky Survey (red,green, and blue).
Source: phys.org