A gargantuan collision

esahubble_potw1802a January 8th, 2018

Credit: ESA/Hubble & NASA, RELICS

In 2014, astronomers using the NASA/ESA Hubble Space Telescope found that this enormous galaxy cluster contains the mass of a staggering three million billion Suns so its little wonder that it has earned the nickname of El Gordo (the Fat One in Spanish)! Known officially as ACT-CLJ0102-4915, it is the largest, hottest, and X-ray brightest galaxy cluster ever discovered in the distant Universe. Galaxy clusters are the largest objects in the Universe that are bound together by gravity. They form over billions of years as smaller groups of galaxies slowly come together. In 2012, observations from ESOs Very Large Telescope, NASAs Chandra X-ray Observatory and the Atacama Cosmology Telescope showed that El Gordo is actually composed of two galaxy clusters colliding at millions of kilometres 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 El Gordos mass is concealed in the form of dark matter. Evidence suggests that El Gordos 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 image was taken by Hubbles Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) to study.

Provider: Hubble Space Telescope | ESA

Image Source: https://www.spacetelescope.org/images/potw1802a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License