Researchers are diving into a synthetic universe to help us better understand reality. Using supercomputers at the U.S. Department of Energy’s Argonne National Laboratory in Illinois, scientists created nearly 4 million simulated images of the cosmos using the Nancy Grace Roman Space Telescope NASA and the Vera C. Rubin Observatory, jointly funded by the NSF (the National Science Foundation) and DOE, in Chile, will see it.
Michael Troxel, an associate professor of physics at Duke University in Durham, North Carolina, led the simulation campaign as part of a larger project called OpenUniverse. The team is now releasing a 10 terabyte subset of this data, with the remaining 390 terabytes expected to follow this fall once processed.
“Using Argonne’s now-retired Theta machine, we accomplished in about nine days what would have taken about 300 years on your laptop,” said Katrin Heitmann, a cosmologist and deputy director of the physics division of the Argonne High Energy, which managed the time of the project’s supercomputer. “The results will shape Roman and Rubin’s future attempts to illuminate dark matter and dark energy while giving other scientists insight into the types of things they can explore using data from the telescopes.”
A cosmic dress rehearsal
For the first time, this simulation took into account the performance of the telescopes’ instruments, making it the most accurate snapshot yet of the cosmos as Roman and Rubin will see it once they start observing. Rubin will begin operations in 2025 and NASA’s Roman will launch by May 2027.
The accuracy of the simulation is important because scientists will examine future data from observatories looking for tiny features that will help them unravel cosmology’s biggest mysteries.
Both Roman and Rubin will explore dark energy, the mysterious force believed to accelerate the expansion of the universe. Since it plays a major role in governing the cosmos, scientists are eager to learn more about it. Simulations like OpenUniverse help them understand the signatures each instrument imprints on images and perfect data processing methods now so they can correctly decipher future data. Scientists will then be able to make great discoveries, even from weak signals.
“OpenUniverse allows us to calibrate our expectations for what we can discover with these telescopes,” said Jim Chiang, a scientist at DOE’s SLAC National Accelerator Laboratory in Menlo Park, Calif., who helped create the simulations. “This gives us the opportunity to exercise our processing pipelines, better understand our analysis codes, and accurately interpret the results so we can prepare to use the real data as soon as it starts coming in.” »
Next, they will continue to use simulations to explore the physics and effects of instruments that could replicate what observatories see in the universe.
Telescopic teamwork
It took a large and talented team from multiple organizations to conduct a simulation of this magnitude.
“Few people in the world are skilled enough to run these simulations,” said Alina Kiessling, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California and principal investigator of OpenUniverse. “This massive undertaking was only possible because of the collaboration between DOE, Argonne, SLAC and NASA, who brought together all the appropriate resources and experts.”
And the project will intensify once Roman and Rubin start observing the universe.
“We will use the observations to make our simulations even more precise,” Kiessling said. “This will give us better insight into how the universe has evolved over time and help us better understand the cosmology that ultimately shaped the universe.”
Roman and Rubin’s simulations cover the same part of the sky, totaling about 0.08 square degrees (roughly the equivalent of a third of the sky area covered by a full Moon). The full simulation, which will be released later this year, will span 70 square degrees, or about the area of the sky covered by 350 full Moons.
Stacking them allows scientists to learn how to use the best aspects of each telescope: Rubin’s broader view and Roman’s sharper, deeper view. This combination will produce better constraints than researchers could obtain from either observatory alone.
“Connecting the simulations the way we did allows us to make comparisons and see how Roman’s space survey will help improve the data from Rubin’s ground-based survey,” Heitmann said. “We can explore ways to distinguish multiple objects that blend together in Rubin images and apply these corrections over a wider coverage.”
Scientists may consider modifying each telescope’s observing plans or data processing pipelines to benefit from the combined use of both.
“We’ve made phenomenal progress in simplifying these pipelines and making them usable,” Kiessling said. A partnership with Caltech/IPAC’s Infrared Science Archive (IRSA) makes the simulated data accessible now, so that when researchers access real data in the future, they will already be accustomed to the tools. “Now we want people to start working with the simulations to see what improvements we can make and prepare to use future data as effectively as possible. »
OpenUniverse, along with other simulation tools developed by Roman’s Science Operations and Science Support Centers, will prepare scientists for the large data sets expected from Roman. The project brings together dozens of experts from NASA’s JPL, DOE’s Argonne, IPAC, and several U.S. universities to coordinate with the Roman Project infrastructure teams, SLAC, and Rubin LSST DESC ( Legacy Survey of Space and Time Dark Energy Science Collaboration). The Theta supercomputer was operated by the Argonne Leadership Computing Facility, a DOE Office of Science user facility.
The Nancy Grace Roman Space Telescope is operated at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation from NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore and a scientific team composed of scientists from various research establishments. Key industry partners include BAE Systems, Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
The Vera C. Rubin Observatory is a federal project jointly funded by the National Science Foundation and the DOE Office of Science, with initial construction funding coming from private donations through the LSST Discovery Alliance.
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By Ashley Balzer
NASA Goddard Space Flight CenterGreenbelt, Maryland.
Media Contact:
Claire Andreoli
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NASA Goddard Space Flight Center, Greenbelt, Maryland.