Gravitational lensing maps from the initial data promise even greater detail. Argonne is part of a multi-institutional effort to explore the skies for clues about the origin and nature of our universe.

Scientists at the South Pole Telescope in Antarctica have been observing the sky with the help of a modernized camera for more than five years. An expanded view of the universe collects light left over from the universe’s early formation. The researchers have now analyzed the first set of data and published the details in a journal. Physical Examination D. The results of this limited data set point to a much stronger future understanding of the nature of our universe.

Breakthrough in cosmic microwave background ray analysis

The telescope, located at the National Science Foundation’s Amundsen-Scott South Pole Station, received a new camera in 2017, known as SPT-3G and currently built and operated by a collaboration led by the University of Chicago.

Equipped with 16,000 detectors, 10 times more than its predecessor, the SPT-3G is at the center of multi-institutional research conducted in part by Argonne National Laboratory. The goal is to measure the faint light known as the cosmic microwave background. The cosmic microwave background is the radiation that emerged after the Big Bang, when the universe exploded from a single point of energy about 14 billion years ago.

“The CMB is a treasure map for cosmologists,” said Zhaodi Pan, lead author of the paper and Maria Heppert Mayer Research Fellow at Argonne. ​“Slight fluctuations in temperature and polarization provide a unique window into the infancy of the universe.”

Gravitational lensing and the study of dark matter

Article entry Physical Examination D Presents the first measurements of the CMB gravitational lens using SPT-3G. Gravitational lensing occurs when the vast network of matter in the universe distorts residual radiation as it travels through space. If you place the curved bottom of a glass over the page of a book, the glass distorts your view of the words behind it. Similarly, the matter in the telescope’s field of view forms a lens that distorts the CMB light and our view of it. Albert Einstein described this distortion in the fabric of space-time in his theory of general relativity.

“CMB is a treasure map for cosmologists. Slight fluctuations in temperature and polarization provide a unique window into the infancy of the universe.” — Zhaodi Pan, Maria Heppert Mayer, Argonne employee

Measuring this distortion holds clues about mysteries such as the early universe and dark matter, an invisible component of the universe. “Dark 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 interaction,” Pan said.

Since its discovery in the 1960s, scientists have been studying the CMB by observing it with telescopes both on the ground and in space. Although the latest analysis used only a few months of SPT-3G data from 2018, measuring gravitational lensing is already competitive in this field.

“One of the really exciting parts of this work is that the result is derived from essentially proprietary data that we just started observing with SPT-3G—and the result is already remarkable,” said Argonne physicist Amy Bender. and co-author of the article. “We have another five years of data that we’re analyzing right now, so these are just a hint of what’s to come.”

Possible directions for future research

The South Pole Telescope’s dry, stable atmosphere and remote location create as few obstacles as possible when searching for CMB diagrams. But the data from the highly sensitive SPT-3G camera includes pollution from our own galaxy and extragalactic sources, as well as the atmosphere. Analyzing even a few months of data from SPT-3G is a years-long endeavor, as researchers must verify the data, filter out noise, and interpret measurements. The team used a special cluster, a group of computers at Argonne Laboratory’s Computing Resource Center to perform some of the study’s calculations.

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

SPT-3G lensing maps derived from additional years of data will also help investigate 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 the theory. The presence of gravitational lensing interferes with bulging traces and requires removal of such contamination, which can be calculated using accurate lensing measurements.

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

“Every time we add more data, we find more things we don’t understand,” said Bender, who hosted the meeting at the University of Chicago. “As you peel back the layers of this onion, you learn more and more about your instrument and your scientific measurements of the sky.”

So little is known about the invisible components of the universe that any understanding is crucial, Pan said: “The more we learn about the distribution of dark matter, the closer we get to understanding its nature and its role in shaping the universe we inhabit.” live. Today”.