Hubble Captures Enormous Galaxy Cluster.
ACT-CLJ0102-4915 is located approximately 7.2 billion light-years from Earth. This galaxy cluster is almost as massive as 3 million billion Suns — so it’s little wonder that it has earned the nickname of ‘El Gordo’ (‘the Fat One’ in Spanish).
In 2012, observations from ESO’s Very Large Telescope, NASA’s Chandra X-ray Observatory and the Atacama Cosmology Telescope showed that ACT-CLJ0102-4915 is composed of two galaxy clusters colliding at millions of miles per hour. The formation of galaxy clusters depends heavily on dark matter, and dark energy; studying such clusters can, therefore, help shed light on these elusive phenomena.
In 2014, Hubble found that most of ACT-CLJ0102-4915’s mass is concealed in the form of dark matter. Evidence suggests that ACT-CLJ0102-4915’s ‘normal’ matter — largely composed of hot gas that is bright in the X-ray wavelength domain — is being torn from the dark matter in the collision. The hot gas is slowing down, while the dark matter is not. This spectacular scene was captured by Hubble’s Advanced Camera for Surveys (ACS) and Wide-Field Camera 3 (WFC3) instruments as part of an extensive observing program called Reionization Lensing Cluster Survey (RELICS). RELICS imaged 41 giant galaxy clusters over the course of 390 Hubble orbits and 100 Spitzer Space Telescope observing hours, aiming to find the brightest distant galaxies. Studying these galaxies in more detail with both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope will hopefully tell us more about our cosmic origins.
Credit: SCI News, 8 January 2018.