![]() ![]() The signals of these patterns are shown in the insets in the accompanying image. From this map, researchers measured patterns in the distribution of galaxies, which gave several key parameters of the universe to better than 1% accuracy. A close look reveals the filaments and voids that define the structure in the universe, starting from the time when it was only about 300,000 years old. The final map is shown in the accompanying image. ![]() So, the location of these signals reveals the expansion rate of the universe at different times in cosmic history. As we look out in distance, we look back in time. The bump visible in each panel is at the characteristic scale of about 500 million lightyears. The inset for each color-coded section of the map includes an image of a typical galaxy or quasar from that section, and also the signal of the pattern that the eBOSS team measures there. We are located at the center of this map. The SDSS map is shown as a rainbow of colors, located within the observable universe (the outer sphere, showing fluctuations in the Cosmic Microwave Background). PHOTO CREDIT: Anand Raichoor (EPFL), Ashley Ross (Ohio State University) and SDSS ![]() “The story underneath the structure growth is amazingly consistent with what we learn from the expansion history.” “The analyses have also provided measurements on how the diverse structures in the universe grow over time,” says Zheng Zheng, professor of physics and astronomy at the U. We also know its expansion history over the last few billion years from galaxy maps and distance measurements, including those from previous phases of the SDSS. We know what the universe looked like in its infancy thanks to thousands of scientists from around the world who have measured the relative amounts of elements created soon after the Big Bang, and who have studied the Cosmic Microwave Background. The results come from the extended Baryon Oscillation Spectroscopic Survey (eBOSS), an international collaboration of more than 100 astrophysicists that is one of the SDSS’s component surveys. “For five years, we have worked to fill in that gap, and we are using that information to provide some of the most substantial advances in cosmology in the last decade.” “We know both the ancient history of the universe and its recent expansion history fairly well, but there’s been a troublesome gap in the middle 11 billion years,” said cosmologist Kyle Dawson of the University of Utah, who led the team announcing today’s results. At the heart of the new results are detailed measurements of more than 2 million galaxies and quasars covering 11 billion years of cosmic time. The Sloan Digital Sky Survey (SDSS) released today a comprehensive analysisof the largest 3-D map of the universe ever created. ![]()
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