A new study uses data collected by the South Pole Telescope, above, to deepen our understanding of how the universe was born and evolved. – AMAN CHOKSHI/UNIVERSITY OF CHICAGO
Nov. 15 () –
Observations from the South Pole primordial light of the universe have reinforced the theoretical foundations of the standard cosmological model that describes the history of the cosmos.
About 400,000 years after the Big Bang, the universe cooled enough to allow photons to escape the primordial cosmological soup. For the next 14 billion years, these ancient photons (the first light of the universe) continued to travel. This residual light is known as the Cosmic Microwave Background (CMB).
In a new study, scientists used high-precision measurements of the cosmic microwave background and its polarized light, collected from the South Pole Telescope located at the National Science Foundation (NSF) Amundsen-Scott South Pole Station. Their findings have been submitted to the journal Physical Review D. and are available on the arXiv preprint server.
“We have a largely coherent, detailed and successful model that describes these 14 billion years of evolution,” he said. in a statement Lloyd Knox, professor of Cosmology and Astrophysics at the University of California Davis and one of the co-authors of the study. “But we don’t know what actually generated the initial deviations from complete homogeneity that eventually led to all structures in the universe, including ourselves.”
“This result is especially exciting, because it represents the first competitive constraints in cosmology using only CMB polarization, making it almost 100% independent of previous results that were based primarily on total intensity,” said study co-author and University of Chicago research professor Tom Crawford.
In the study, researchers analyzed two years of polarized light data collected by the South Polo Telescope in 2019 and 2020. The study’s observations cover 1,500 square degrees of sky and the data collected allowed researchers to create a large-scale map of the mass of the universe.
Most natural light is not polarized, it is composed of a random collection of light waves, each oscillating (waving up and down) without a preferred direction. But when light is reflected, it can become polarized, meaning the light oscillates in a preferred direction.
This happens when sunlight reflects off water or the ground, and is why polarized sunglasses can be so useful for reducing glare. It also happened when photons from the cosmic microwave background experienced their final scattering events in the primordial plasma. when it began to disappear 14 billion years ago.
“The light from the cosmic microwave background is partially polarized,” Knox said. “We are measuring at each point on our sky map the degree of polarization and the orientation of the polarization.”
After that last scattering, the slightly polarized light diffused across the open space. Gravitational forces distort the paths of these light rays. Light from different regions is also distorted differently, resulting in a warped image, an effect called gravitational lensing.
To discover both what the polarized image would look like in the absence of gravitational lensing and also the map of the mass causing gravitational lensing, the team used computers at the National Energy Research Scientific Computing Center (NERSC) in Berkeley.
“What we essentially do at a very high level is take this data and send it to this supercomputer at NERSC,” said Marius Millea, a project scientist in Knox’s research group and the second author of the study. “And computers are testing this idea: ‘If this were what the real universe looked like, would it produce a map that looked like the one we saw?'”
“We have the data, but we also need to have a model that produces or predicts these types of observables“added Fei Ge, a graduate student in Knox’s research group and the first author of the study.
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