Fat, big, large, massive- translates el gord in spanish. This name is given to the largest distant galaxy cluster discovered, also known as ACT-CL J0102-4915. Felipe Menanteau, a Research Scientist at the National Center for Supercomputing Applications, states, "This cluster is the most massive, the hottest, and gives off the most X-rays of any known cluster at this distance or beyond." Menanteau describes the characteristics of this enormous cluster unlike any seen before. El Gordo is located approximately 9.7 billion light years away from Earth and its mass is measured three billion times as much as our sun. A cluster unlike any previously discovered.
The photo for April 22, 2014 of “El Gorgo Massive Galaxy Cluster” stuck out from other pictures taken on NASA’s Astronomy Picture of The Day. The appearance of this galaxy was especially fascinating. I was drawn by the image’s bright spots and blue and pink colors. The image is a combination of a visible light image by the Hubble Space Telescope in 2002, an X-ray image from the Chandra Observatory of the hot gas in pink in 2014, and computer generated dark matter in blue through gravitational lens distortions. The bright spots in the image are galaxies within and beyond the cluster. Remains of radiation from the Big Bang along with electrons from hot gas in the galaxy cluster creates the warping seen from earth. Hubble's high resolution shows the distortion in space caused by gravity. This warps the background of galaxies in the image. The more mass in the cluster the larger the distortions. The long vertical galaxy in the image is far more distant and the light is being stretched as it travels towards us through gravitational lens caused by the massive cluster. The pink color across the image is the hot gas that was slowed down by the collision. The blue color across the picture is dark matter which reveals the cluster is in the middle stages of the collision between the two large galaxy clusters.
El Gordo is classified as a galaxy cluster. Galaxy clusters are the largest bound objects known in the entire universe. It contains hundreds of galaxies with planets, stars, gas, and dust all bound together by gravity. Clusters contain clouds of hot gas as well. And also dark matter, which is not visible or detected but is believed to be present through the gravitational pull on the galaxies and hot gas. The formation of galaxy clusters occurs when smaller galaxies come together. El Gordo is believed to be the result of a collision between two separate galaxy subclusters. This is possible through the amount of hot gas and dark matter in the universe at the given time.
The European’s Very Large Telescope array in Paranal, Chile measured the clusters velocity based on hot gas temperatures between the cluster galaxies. It was also measured through the movement of galaxies within the cluster. However, new scientific discoveries were made regarding El Gordo. Data from the Hubble Space Telescope indicates the galaxy cluster weighs 3 million billion times the mass of our Sun. This is 43 percent higher than earlier estimates.
There is a lot of information that is still unknown about the El Gordo galaxy cluster. And as technology advances, so does the ability to discover more about our universe. Astronomy is so complex and happens at such a large scale, there is so much more information to discover. Countless unknown and unattainable factors lie in space. John Hughes from Rutgers University states,”We wondered what happens when you catch a cluster in the midst of a major merger and how the merger process influences both the X-ray gas and the motion of the galaxies. So, the bottom line is because of the complicated merger state, it left some questions about the reliability of the mass estimates we were making." This pertains to the size of El Gordo and how it was previously measured much smaller than it is believed to be today. This discovery made was only two years after it was first estimated. This illustrates what Hughes means when he states that it questions the accuracy of the mass they are calculating. Another factor Astronomers are uncertain about is dark energy. As galaxy clusters merge together, it affects the line of sight for observers on earth. This creates the expectation of “unaccounted energy.” A large amount of kinetic energy is being unaccounted given how gravity works with all the galaxies, stars, gas, and dust within the cluster. Large portions of the clusters mass, hot gas, and dark matter are in the hundreds of galaxies within the cluster. Given the structure of the galaxy cluster, it is believed that dark matter exist but cannot be physically proven. New discoveries in space may change this theory completely. However, even given El Gordo’s rare size and distance, it still follows astronomers’ current theories and beliefs of the Big Bang and dark matter and dark energy.
There is still future plans for El Gordo. Given its massive size and distance from earth, there is a great deal of information waiting to be discovered. According to Science Daily the team's future plans are to create an image of El Gordo. However, given the Hubble telescope’s field of view and the clusters massive size, the team plans to take multiple images to be compiled into a mosaic.
