On a mountain in northern Chile, scientists carefully assemble the complex components of the NSF-DOE Vera C. Rubin Observatory, one of the most advanced astronomical facilities in history.
Equipped with an innovative telescope and the world’s largest digital camera, the observatory will soon begin the Legacy Survey of Space and Time (LSST).
During LSST’s 10 years of space exploration, the Rubin Observatory will take 5.5 million data-rich images of the sky. Larger and deeper than all previous studies combined, LSST will provide an unprecedented amount of information to astronomers and cosmologists working to answer some of the most fundamental questions in science.
Deeply involved in the LSST Dark Energy Science Collaboration (DESC), scientists at DOE’s Argonne National Laboratory are working to uncover the true nature of dark energy and matter.
In preparation for LSST, they are performing advanced cosmological simulations and collaborating with the Rubin Observatory to model and process the data to maximize discovery potential.
Together, dark energy and dark matter make up 95% of the energy and matter in the Universe, but scientists understand very little about them.
They see the effects of dark matter in the formation and motion of galaxies, but when they look for it, it doesn’t seem to exist. Meanwhile, space itself is expanding faster and faster over time, and scientists don’t know why. They refer to this unknown influence as dark energy.
95% of the energy and matter of the Universe
“Right now, we have no clue as to their physical origins, but we do have theories,” said Katrin Heitmann, deputy director of Argonne’s High Energy Physics (HEP) division. “With the help of LSST and the Rubin Observatory, we really believe we can get good constraints on what dark matter and energy might be, which will help the community pursue the most promising directions.”
In preparation for LSST, Argonne scientists take theories about certain attributes of matter and dark energy and simulate the evolution of the universe based on those assumptions.
It is important that scientists find ways to match their theories with the signatures that the survey can actually detect.
The simulations can help researchers analyze what features will actually appear in real-world data from LSST that would reveal a particular theory to be true.
The simulations also allow the collaboration to validate the code they will use to process and analyze the data.
Scientists simulate the evolution of the Universe
For example, together with LSST DESC and the collaboration behind NASA’s Nancy Grace Roman Space Telescope, Argonne scientists recently simulated images of the night sky as each telescope will actually see them. To make sure their software works as expected, scientists can test it on these clean simulated images before they begin processing real images.
To perform their simulations, Argonne scientists use the computing resources of the Argonne Leadership Computing Facility (ALCF), a DOE Office of Science utility facility. Among its suite of supercomputers, ALCF hosts Aurora, one of the world’s first exascale machines, which can perform more than a quintillion – or a trillion billion – calculations per second, he writes Phys.org.
“Aurora’s impressive memory and speed will allow us to simulate larger volumes of the Universe and consider more physics in our simulations than ever before, while maintaining a high enough resolution to capture important details,” Heitmann said. , who was previously the spokesperson of LSST DESC.
During LSST, light emitted long ago by distant galaxies will reach the observatory.
Weak gravitational lensing
Sensors on the observatory’s camera will convert the light into data, which will travel from the mountain to several Rubin Project data centers around the world. These facilities will then prepare the data to be sent to the wider community for analysis.
As part of LSST DESC, Argonne scientists are currently collaborating with the Rubin Observatory to ensure that the data is processed in the most favorable way for their scientific goals. For example, Argonne physicist Matthew Becker is working closely with the Rubin project to develop data-processing algorithms that will enable the investigation of dark matter and energy through a phenomenon called weak gravitational lensing.
Weak gravitational lensing can also reveal how the structure of the universe has changed over time, which could shed light on the nature of dark energy.
The challenge is that the signals indicating a weak gravitational lens in the LSST data will be weak. The signal strength scientists are looking for will be about 30 times less than the expected level of noise, or unwanted signal disturbance, in the data.
This means scientists need a lot of data to make sure their measurements are accurate, and they’re about to get it. Once complete, LSST will generate 60 petabytes of image data, or 60 million gigabytes. It would take over 11,000 years of Netflix viewing to use that amount of data.
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Source: www.descopera.ro
