3D map of galaxies reveals treasures of the Cosmos
The Sloan Digital Sky Survey (SDSS) have released a comprehensive analysis of the largest three-dimensional galaxy map of the Universe ever created, filling in the most significant gaps in our exploration of its history over 11 billion years of cosmic time.
The new results are detailed measurements of more than two million galaxies and quasars, derived from a subset of the SDSS: the extended Baryon Oscillation Spectroscopic Survey (eBOSS), which involved an international collaboration of more than 100 astrophysicists.
The detailed analysis of this dataset is described in more that 20 technical papers which the eBOSS team have made public. These papers, more than 500 pages in total, mark the completion of the key goals of the survey. Within the eBOSS team, individual groups at universities around the world focused on different aspects of the analysis. To create the part of the map dating back six billion years, the team used luminous red galaxies. Farther out, they used younger blue galaxies. Finally, to map the Universe eleven billion years in the past and more, they used quasars, which are bright galaxies lit up by material falling onto a central supermassive black hole. Each of these samples required careful analysis in order to remove contaminants and reveal the patterns of the Universe.
The team from the Institute of Astronomy at the School of Physics and Astronomy, including Dr Shadab Alam and Prof John Peacock, led an analysis focused on understanding the young blue galaxies. There is a long-standing question of nature vs nurture when one looks at the populations of different types of galaxies. More precisely, what aspects of the galaxy properties are affected by the local conditions around these galaxies? Such questions are interesting in their own right, but they are also particularly important to make sure our measurements of the properties of the Universe are not biased by local conditions of these galaxies.
The wealth of data released by the eBOSS team will continue to be one of richest datasets for astronomers to attack some of the most challenging questions in astrophysics.
The effort from the University of Edinburgh was supported by the European Research Council through the COSFORM Research Grant.