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In Antarctica, at the extreme south of our planet, is a 33-foot telescope designed for one purpose: to create images of the oldest light in the universe.
This light, known as the cosmic microwave background, crossed the cosmos for 14 billion years, moments that immediately followed the Big Bang so far. Because it is the brightest in the microwave part of the spectrum, the CMB is impossible to see with our eyes and requires specialized telescopes.
The South Pole Telescope, specifically designed to measure CMB, recently opened its third-generation camera for a multi-year study to observe the first moments of the universe. Since 2007, the SPT has highlighted the physics of black holes, discovered a cluster of galaxies producing stars at the highest level ever seen, redefined our image of the moment when the first stars were formed in the universe, on the masses. neutrinos. This latest upgrade enhances its sensitivity by almost an order of magnitude, making it one of the most responsive CMB instruments ever built.
"Being able to detect and analyze the CMB, especially with this level of detail, is like having a time machine to go back to the first moments of our universe," says researcher John Carlstrom. South Pole Head at the University of Chicago Telescope Project.
"Encoded in the images of the CMB light we capture, it's the story of what this light has come across in its 14 billion year journey across the cosmos," he says. . "From these images, we can tell what the universe is made of, how the universe turned out to be extremely young and how the universe evolved."
Located at the Amundsen-Scott South Pole Station of the National Science Foundation, the South Pole Telescope is funded and maintained by the National Science Foundation as the head of the US Antarctic Program, the national research program on the southernmost continent.
"The ability to use a 10-meter telescope, literally at the end of the Earth, testifies to the scientific capabilities of the NSF-supported researchers and the sophisticated logistic support that NSF and its partners are able to provide in one of the Earth's harshest environments, "says Vladimir Papitashvili, director of the Antarctic Geophysical Astrophysics and Geospatial Science Program at the NSF Polar Programs Office. "This new camera will expand the capabilities of an already impressive instrument."
The telescope is operated by more than 80 scientists and engineers from a group of US Department of Energy universities and national laboratories, including three institutions in the Chicago area. These research organizations – the University of Chicago, the Argonne National Laboratory and the Fermilab National Accelerator Laboratory – have collaborated on the construction of a new ultrasensitive camera for the telescope, containing 16,000 specially manufactured detectors.
"Built with state-of-the-art sensing technology, this new camera will dramatically improve the search for the signature of early cosmic inflation in the cosmic microwave background and allow us to penetrate other fundamental mysteries of the universe, including the nature of dark energy, "says Kathy Turner of the DOE Bureau of Science.
"Baby pictures" of the cosmos
The CMB is the oldest light in our universe, produced as a result of the intense heat of the Big Bang even before the formation of atoms. These primordial light particles, which have remained almost intact for nearly 14 billion years, provide unique clues to how the universe has looked at the beginning of time and its evolution ever since.
"This relic light is still incredibly bright – literally surpassing all stars in the universe's history by more than an order of magnitude in energy," says Bradford Benson, a professor at the University of Chicago and a scientist at Fermilab. . build this new camera.
However, since most of the energy lies in the microwave part of the spectrum, it is necessary, to observe it, to use special detectors in observatories located in high places and dry. The South Pole Station is better than anywhere else on Earth: it is located at the top of an ice sheet two miles thick and the extremely low temperatures of Antarctica make it "easy". there is almost no atmospheric water vapor.
Scientists hope to take advantage of this data to obtain information on a number of physical processes and even new particles.
"The cosmic microwave background is a remarkably rich source of scientific data," says Benson. "The third-generation camera survey can give us clues about everything from dark energy to Big Bang physics, to the location of the most massive galaxy groups in the universe.
The details of this "baby photo" of the cosmos will allow scientists to better understand the different types of matter and energy that make up our universe, such as neutrinos and dark energy. They can even find evidence of gravitational waves since the beginning of the universe, considered by many as the "smoking rifle" of the theory of inflation. It also serves as a rich astronomical survey; One of the things they are looking for is some of the first massive galaxies in the universe. These huge galaxies are increasingly interesting to astronomers as "stellar farms", forming the first stars of the universe.
"Nothing coming out of a box"
The collaboration with the South Pole Telescope has been operating the telescope since it was built in 2007. Grants from several sources – the National Science Foundation, the US Department of Energy, and the Kavli and Moore Foundations – supported a second polarization-sensitive camera. generation. The latest third generation focal plane contains 10 times more detectors than previous experience, requiring new ideas and solutions in materials and nanoscience.
"From a technology point of view, there's almost nothing out of the box," says Clarence Chang, an assistant professor at the University of Chicago and a physicist in Argonne.
For the South Pole telescope, scientists needed much more sensitive equipment than anything that was commercial. They had to develop their own detectors, which use special materials to detect tiny changes in temperature when they absorb light. These custom detectors have been developed and manufactured from scratch in Argonne's ultraclean rooms.
The detectors were handed over to Fermilab for assembly into modules, which included small lenses for each pixel made at the University of Illinois at Urbana-Champaign. After being tested at several collaborating universities across the country, the detectors returned to Fermilab to be integrated into the camera cryostat of the South Pole telescope, designed by Benson. The camera looks like an 8 meter high optical camera and 2,500 pounds with a telephoto lens on the front, but with the added complication that the lenses need to be cooled to a few degrees above absolute zero. (Even Antarctica is not so cold, so it needs this special cryostat to cool it further.)
Finally, the new camera was ready for its 10,000-mile trip to Antarctica by land, air and sea. In the final leg, from NSF's McMurdo Station to the South Pole, he flew aboard an LC130 cargo plane equipped with skis to land on the snow near the telescope site, as the station rests on an ice cap . The components were carefully unloaded and a team of more than 30 scientists participated in a camera rally during the short three-month summer in Antarctica, as the South Pole is not accessible by air for most of the day. year. 100 degrees Fahrenheit.
The multi-year observation campaign for the South Pole Telescope brings together researchers from North America, Europe and Australia. With the upgrade of the telescope data, the exploration of cosmic microwave background radiation is entering a new era with powerful collaboration and an extremely sensitive instrument.
"The CMB study involves many different types of scientific trips," says Chang. "It's exciting to see everyone's efforts come together to push the boundaries of what we know."
Editor's Note: This article is adapted from a press release from Fermilab.
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