Where does our universe come from and has its composition changed over time? Scientists have new ideas on these fundamental issues, thanks to an international collaboration of more than 400 scientists called the Dark Energy Survey (DES). Three scientists at the NASA Jet Propulsion Laboratory in Pasadena, California, are part of this group that fosters our understanding of the structure of the universe.
Advances in DES astrophysics is critical for the preparation of the next two space missions similar questions about the nature of the universe will examine: ESA’s Euclid mission (with significant NASA involvement) and the mission of the Great Image Infrared NASA, both expected launch in the 2020s.
“With this study, we are showcasing what’s going to be possible with these much more complex observatories,” said Andres Plazas Malagón, a postdoctoral researcher at JPL who helped characterize the DES’s Dark Energy camera detector and also participates in WFIRST detector studies.
The main models of the universe suggest that it is composed mainly of entities we can not see: dark matter and dark energy. Dark matter acts as the invisible glue that keeps galaxies and galaxy clusters together in gravity, while dark energy is considered to be responsible for the accelerated expansion of the universe. Some of our best predictions of how dark matter and dark energy in the universe come from the European Space Agency’s Planck satellite, which looks down from about 400,000 years after the Big Bang into the light.
Now the Dark Energy Survey examined the composition of the recent Universe. Surprisingly, the new results are close to Planck’s predictions of distant past measurements, allowing scientists to understand more about how the universe has evolved in 14 billion years. The results were announced in a presentation at the American Physical Society’s Particle and Field Division at the United States Department of Energy’s Fermi National Accelerator Laboratory in Batavia, Illinois.
“The Planck results have been the landmark constraints in cosmology. It is truly amazing that you have a model that describes the universe at 400,000 years old, and now we have a similarly precise measurement of the universe at 13 billion years [old] that agrees with the model,” said the JPL by Tim Eifler, which the Dark Energy Survey’s analysis team led that developed the science software for interpreting the results.
Scientists found that about 70 percent of the energy in the universe is contained in dark energy. About 25 percent is composed of dark matter, which is the rest of the normal matter. All this is in accordance with the precise measurements to date. DES has so far found no evidence that the amount of dark energy has changed over time – a finding that is consistent with Albert Einstein’s idea of a ‘cosmological constant’.
The results are especially important to the scientific community, as they are the first notice that the comments of the most recent universe – the ‘mature’ universe – a technique called gravitational lensing and clustering of galaxies, are as accurate as a consequence of Cosmic background radiation – vision of the ‘child’ universe.
“This is the crossover point where gravitational lensing and galaxy clustering measurements and surveys will be the primary driver of what we know about dark energy in the universe,” said Eric Huff, a JPL researcher who developed a New method for weak lens signal extraction, which increases the accuracy of form des Galaxy catalogs.
The results come from the first year data series of the Dark Energy Survey, which uses a 570-megapixel camera in the 4-meter White telescope at the Inter-American Observatory of the National Observatory of Optical Astronomy in Chile. Data are processed at the National Center for Supercomputer Applications at the University of Illinois at Urbana-Champaign.
To measure dark matter, scientists created first maps of galaxy positions. They then carefully measured the shapes of galaxies 26 million to spend directly assigning the patterns of dark matter in millions of light years through gravitational lenses and clustering of galaxies.
The DES-team developed new ways to detect the small distortion of the galaxy image lens. In the process they created the greatest guide to discover dark matter in the ever-signed cosmos. The new dark material map is 10 times as large as the DES issued in 2015 and continues to grow.
The DES collaboration will be five times greater in the next two years in a data set.
“There is a feeling of true discovery in the collaboration. For the first time, we have the data and tools in hand to see whether Einstein’s cosmological constant prevails. We are all excited to explore the physical nature of dark energy,” Eifler said. “In particular we want to see if there are hints in the data that suggest modifying the laws of gravity on the largest scales in the universe.”
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