This image of Galaxy Cluster MS 0735.6+7421 combines data from the Chandra X-Ray observatory, Hubble Space Telescope, and Very Large Array in new Mexico. This cluster contains dozens of galaxies held together by gravity. The red jets come from a Black Hole with a billion (10^9) times the mass of our Sun! The jets displace 10^12, a trillion solar masses of gas.
The blue regions are hot gas filling the space between galaxies. Cavities within the gas are filled with charged particles spiralling around magnetic field lines. These cavities are 640,000 light-years in diameter, nearly seven times the size of our galaxy. These are also possible locations of Black Holes.
According to theories of "dark energy," 5 billion years ago its repulsive force would have begun to dominate. Formation of galaxy clusters would have ceased as repulsion overcame gravity. We would see more clusters in the past than exist today. Astronomers have found FEWER clusters in the past, telling us that clusters are still forming. Rather than tearing itself apart with "dark energy," the Universe continues to form more complex structures.
Results from Chandra and the XMM-Newton spacecraft show that attractive "dark" mass is 4 times as abundant as previously thought. Instead of just 24%, dark stuff comprises the 95% of the Universe that is not baryons. There is no need for a repulsive "dark energy" to fill the rest. Our 4.507034% of light-emitting matter is just a footnote. We are the lights hinting at something else in the darkness.