11 October 2023<\/p>\n\n\n\n
Rubin Observatory\u2019s Legacy Survey of Space and Time will help scientists map the large-scale structure of the Universe with finer precision than ever before. With Rubin\u2019s wide field of view and high resolution, the subtle distortions of galaxy shapes caused by dark matter will be detectable, allowing scientists to map dark matter and explore its cosmic tug of war with dark energy.<\/p>\n\n\n\n
Everything we know \u2014 galaxies, stars, planets, our families, friends, and even pets \u2014 makes up just 5% of the Universe. The remaining 95% is made up of mysterious components that scientists call dark energy<\/a> (68%) and dark matter<\/a> (27%). What are they, and how do they influence the structure and evolution of the Universe? Researchers like Andr\u00e9s Alejandro Plazas Malag\u00f3n, Rubin Operations Scientist at SLAC National Laboratory<\/a> and Community Scientist and Calibration Scientist at Rubin Observatory<\/a>, hope to tackle these questions with the upcoming Legacy Survey of Space and Time (LSST)<\/a>, conducted with Rubin Observatory in Chile. With its immense sky coverage and ability to detect faint objects, Rubin\u2019s LSST will provide scientists with the enormous dataset needed to unravel these and other mysteries of the Universe.<\/p>\n\n\n\n In the 1970s American astronomer Vera C. Rubin<\/a> provided the most convincing evidence at that time for the existence of an unseen \u2018dark\u2019 matter in the Universe. Dark matter is called dark because that\u2019s pretty much all we know about it, other than its gravitational influence on stars and gas in galaxies: it\u2019s a substance in the Universe that has mass but doesn\u2019t give off or reflect light. This invisible material makes up about 80% of all matter, and its properties affect how the Universe evolves \u2014 how galaxies form and grow as well as how they clump together to form long filaments that make up the structure scientists call the cosmic web.<\/p>\n\n\n\n But shaping the large-scale structure of the Universe is a game of cosmic tug-of-war between dark matter and an elusive force known as dark energy. \u201cYou can think of dark matter as trying to build the cosmic structures, while dark energy is actually trying to dilute them and push them apart,\u201d<\/em> says Plazas Malag\u00f3n. Most scientists think that dark energy drives the accelerating expansion of the Universe, and that its behavior is described by a quantity known as the cosmological constant<\/a>. This explanation is commonly agreed on because it aligns with the evidence we\u2019ve collected so far. But, while the cosmological constant is currently a fundamental piece of the equations that describe the Universe, researchers are still trying to pin down its exact value \u2014 and whether it\u2019s the explanation for dark energy at all.<\/p>\n\n\n\n Calculating the cosmological constant, and thus placing firm constraints on the equations describing the Universe, is an effort at the forefront of cosmology. And Rubin will enable the most precise measurements of it yet by opening new possibilities for using a subtle effect called weak gravitational lensing<\/a> to explore the complex interplay between dark matter and dark energy.<\/p>\n\n\n\n Cosmologists use weak lensing to infer the \u2018clumpiness\u2019 of matter by observing how its gravity bends light. But unlike strong gravitational lensing<\/a>, which often produces giant, beautiful arcs<\/a> around clusters of galaxies, weak lensing produces effects that are less dramatic: tiny distortions of the light from distant galaxies. While weak lensing can occur at the outskirts of a strong lensing system, it also exists everywhere across the Universe as light from background galaxies makes its way through the filaments of galaxies connecting galaxy clusters and superclusters known as the cosmic web<\/a>. \u201cIf strong lensing is like looking through the bottom of a wine glass, weak lensing is like looking through a large, very subtly warped window,\u201d <\/em>says Theo Schutt, a PhD candidate at Stanford University<\/a> who collaborates with Plazas Malag\u00f3n.<\/p>\n\n\n\n These weak distortions of distant galaxies are too slight to be measured by observing just a single galaxy \u2014 even with data from thousands of galaxies, scientists can\u2019t tell whether individual galaxies\u2019 observed shapes are their true shapes or whether they\u2019ve been distorted by weak lensing. To really understand the big picture, they need a big dataset to calculate the collective distortion across the entire observable sky. Rubin Observatory, with its ability to observe huge patches of the sky while also being able to see very faint and distant galaxies, will be the first observatory in history to provide data on not just millions, but billions<\/em> of galaxies and their shapes.<\/p>\n\n\n\n Rubin Observatory will be a leading resource for cutting-edge astronomy and astrophysics when it comes online in 2025. Using an 8.4-meter telescope equipped with the largest digital camera in the world<\/a>, it will scan the entire southern hemisphere sky every few nights for ten years, providing the most comprehensive view of the Universe we\u2019ve ever seen. Rubin Observatory is jointly funded by the National Science Foundation (NSF<\/a>) and the US Department of Energy (DOE<\/a>). Rubin<\/a> is a Program of NSF\u2019s NOIRLab<\/a>, which, along with SLAC National Accelerator Laboratory<\/a>, will operate Rubin.<\/p>\n\n\n\n Current surveys, such as the Dark Energy Survey<\/a>, the Hyper Suprime Cam<\/a> survey, and the Kilo-Degree Survey<\/a>, are already untangling some of the mysteries of dark matter and dark energy. But there is a trade-off, explains Plazas Malag\u00f3n, between a wide survey and a deep survey, limited by factors such as camera size and resolving power. The LSST Camera<\/a> at Rubin Observatory has the unmatched wide-field view and high resolution that give astronomers and astrophysicists the best of both worlds. In fact, Rubin Observatory was designed from the start<\/a> to help scientists map dark matter in the Universe using gravitational lensing of billions of distant galaxies.<\/p>\n\n\n\n \u201cWith Rubin, we\u2019re going to have everything,\u201d<\/em> said Plazas Malag\u00f3n. \u201cWe\u2019re going to measure the properties of vastly more galaxies than what we have now, which is going to give us the statistical power to use weak lensing to both map the distribution of dark matter and study how dark energy evolves with time.\u201d<\/em><\/p>\n\n\n\n It\u2019s also possible that Rubin will produce new evidence to support alternative explanations for the phenomena we observe in our Universe beyond the most common theories of dark matter and dark energy.<\/p>\n\n\n\n \u201cDark energy is a concept that fits with the accepted theory of gravity within Einstein\u2019s general theory of relativity,\u201d<\/em> said Plazas Malag\u00f3n, \u201cbut Rubin and the LSST will also allow us to explore alternatives to that, which is incredibly exciting as well.\u201d<\/em><\/p>\n\n\n\n Rubin Observatory is a joint initiative of the National Science Foundation (NSF<\/a>) and the Department of Energy (DOE<\/a>). Its primary mission is to carry out the Legacy Survey of Space and Time, providing an unprecedented data set for scientific research supported by both agencies. Rubin is operated jointly by NSF\u2019s NOIRLab<\/a> and SLAC<\/a> National Accelerator Laboratory (SLAC). NOIRLab is managed for NSF by the Association of Universities for Research in Astronomy (AURA<\/a>) and SLAC is operated for DOE by Stanford University<\/a>. Additional contributions from a number of international organizations and teams are acknowledged.<\/p>\n\n\n\n The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 to promote the progress of science. NSF supports basic research and people to create knowledge that transforms the future.<\/p>\n\n\n\n SLAC is operated by Stanford University for the US Department of Energy\u2019s Office of Science<\/a>. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.<\/p>\n\n\n\n NSF\u2019s NOIRLab<\/a> (National Optical-Infrared Astronomy Research Laboratory), the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory<\/a> (a facility of NSF<\/a>, NRC\u2013Canada<\/a>, ANID\u2013Chile<\/a>, MCTIC\u2013Brazil<\/a>, MINCyT\u2013Argentina<\/a>, and KASI\u2013Republic of Korea<\/a>), Kitt Peak National Observatory (KPNO<\/a>), Cerro Tololo Inter-American Observatory (CTIO<\/a>), the Community Science and Data Center (CSDC<\/a>), and Vera C. Rubin Observatory<\/a> (in cooperation with DOE<\/a>\u2019s SLAC<\/a> National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA<\/a>) under a cooperative agreement with NSF<\/a> and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du\u2019ag (Kitt Peak) in Arizona, on Maunakea in Hawai\u2018i, and on Cerro Tololo and Cerro Pach\u00f3n in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O\u2019odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.<\/p>\n\n\n\nMore information<\/h3>\n\n\n\n
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