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Results from the new South Pole Telescope camera revealed


Argonne is part of a multi-institutional effort to study the skies for clues to the origins and nature of our universe.

For more than five years, scientists at the South Pole Telescope in Antarctica have been observing the sky with an improved camera. The gaze extended towards the cosmos captures the residual light from the initial formation of the universe. The researchers have now analyzed a first batch of data and published details in the journal Physical Review D. The results from this limited data set hint at even more powerful future insights into the nature of our universe.

The telescope at the Amundsen-Scott South Pole Station, operated by the National Science Foundation, received a new camera known as the SPT-3G in 2017. Equipped with 16,000 detectors — 10 times more than its predecessor — SPT-3G is at the heart of multi-institutional research led in part by the U.S. Department of Energy’s (DOE) Argonne National Laboratory. The goal is to measure the faint light known as the cosmic microwave background (CMB). The CMB is the afterglow of the Big Bang, when the universe arose from a single point of energy nearly 14 billion years ago.

“The CMB is a treasure map for cosmologists,” said Zhaodi Pan, lead author of the paper and a researcher. Maria Goeppert Mayer, scholarship holder in Argonne. “Its tiny variations in temperature and polarization provide a unique window into the early universe.

THE paper in Physical Review D offers the first CMB gravitational lensing measurements of SPT-3G. Gravitational lensing occurs when the universe’s vast web of matter distorts the CMB as it travels through space. If you were to place the curved base of a wine glass on the page of a book, the glass would distort your view of the words behind it. Similarly, matter in the telescope’s line of sight forms a lens that bends the CMB light and our view of it. Albert Einstein described this distortion of the structure of space-time in his theory of general economics. relativity.

“The CMB is a treasure map for cosmologists. Its tiny variations in temperature and polarization open a unique window into the beginnings of the universe. — Zhaodi Pan, Maria Goeppert Mayer Fellow at Argonne

Measurements of this distortion hold clues to the early universe and mysteries like black matter, an invisible component of the cosmos. “Black matter is difficult to detect because it does not interact with light or other forms of electromagnetic radiation. Currently, we can only observe it through gravitational interactions,” Pan said.

Scientists have studied the CMB since its discovery in the 1960s, observing it using telescopes on the ground and in space. Even though the most recent analysis uses only a few months of SPT-3G data from 2018, the gravitational lensing measurement is already competitive in the field.

“One of the most exciting parts of this study is that the result basically comes from collecting data from when observations began with SPT-3G – and the result is already excellent,” said Argonne physicist Amy Bender. and co-author of the article. “We have another five years of data that we’re working on now, so this is just indicative of what’s to come.”

The dry, stable atmosphere and remote location of the South Pole telescope create as little interference as possible when searching for CMB patterns. Yet data from the highly sensitive SPT-3G camera contains contamination from the atmosphere, as well as our own galaxy and extragalactic sources. Analyzing even a few months of SPT-3G data is a years-long endeavor, as researchers must validate the data, filter out the noise, and interpret the measurements. The team used a dedicated cluster, a group of computers, at Argonne Laboratory Computing Resource Center to perform certain calculations for research.

“We found that the lensing patterns observed in this study are well explained by general relativity,” Pan said. “This suggests that our current understanding of gravity is valid for these large scales. The results also strengthen our current understanding of how matter structures formed in our universe.

SPT-3G lens maps from additional years of data will also help probe cosmic inflation, or the idea that the early universe underwent rapid exponential expansion. Cosmic inflation is “another cornerstone of cosmology,” Pan noted, and scientists are looking for signs of early gravitational waves and other direct evidence for this theory. The presence of gravitational lenses introduces interference with inflationary imprints, requiring removal of this contamination, which can be calculated using precise lensing measurements.

While some results from the new SPT-3G data will reinforce existing knowledge, others will raise new questions.

“Every time we add data, we discover more things we don’t understand,” said Bender, who holds a joint appointment at the University of Chicago. “As you peel back the layers of this onion, you learn more and more about your instrument as well as your scientific measurements of the sky.”

So little is known about the invisible components of the universe that any understanding gained is essential, Pan said: “The more we learn about the distribution of black matterthe closer we come to understanding its nature and its role in shaping the universe we live in today.

This work was supported by the Office of Polar Programs of the National Science Foundation and the High Energy Physics Program of the DOE Office of Science. The scientific analysis was led by Pan, in close collaboration with co-lead authors WL Kimmy Wu and Federico Bianchini (SLAC National Laboratory) and the SPT-3G collaboration. Argonne-affiliated co-authors with Bender and Pan are Lindsey Bleem, Karen Byrum, John Carlstrom, Faustin Carter (Argonne alumnus), Thomas Cecil, Clarence Chang, Junjia Ding (Argonne alumnus), Riccardo Gualtieri ( Argonne alumnus), Angelina Harke-Hosemann (Argonne alumnus), Jason Henning (Argonne alumnus), Florian Kéruzoré, Trupti Khaire (Argonne alumnus), Steve Kuhlmann, Valentine Novosad, John Pearson , Chrystian Posada (Argonne alumnus), Gensheng Wang and Volodymyr Yefremenko.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts cutting-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state, and municipal agencies to help them solve their specific problems, advance America’s scientific leadership, and prepare for the nation to a better future. With employees from more than 60 countries, Argonne is led by UChicago Argonne, LLC for the US Department of Energy Office of Science.

US Department of Energy Office of Science is the largest supporter of basic research in the physical sciences in the United States and strives to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.


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