A ‘less crowded’ universe may suggest the existence of mysterious forces | Astronomy

One of the most accurate studies of the structure of the universe has suggested it’s “less clumped” than previously thought, in findings that could point to the existence of mysterious forces at work.

Observations from the Dark Energy Survey and the South Pole Telescope map the distribution of matter with the goal of understanding the competing forces that have shaped the evolution of the universe and govern its ultimate fate. The extraordinarily detailed analysis adds to a body of evidence that suggests there may be a crucial element missing in the so-called Standard Model of physics.

“There seems to be a little less [clumpiness] in the current universe than we expected assuming our standard cosmological model was rooted in the early universe,” said Eric Baxter, an astrophysicist at the University of Hawaii and co-author of the study.

The results did not cross the statistical threshold that scientists consider armored enough to claim a discovery, but they come after similar results from previous investigations that hinted that a rift could be opening between theoretical predictions and what what really happens in the universe. .

“If the discovery holds, it’s very exciting,” said Dr. Chihway Chang, a University of Chicago astrophysicist and lead author. “The purpose of physics is to test patterns and break them. The best case scenario is that it helps us better understand the nature of dark matter and dark energy.

Since the big bang 13 billion years ago, the universe has expanded, but matter has also cooled and clumped together as gravity pulls denser areas together, creating a cosmic web of clusters and galaxy filaments. As scientists struggled to understand this cosmic tussle, a bizarre picture emerged in which only about 5% of the universe’s content is represented by ordinary matter. About 25% is so-called dark matter, an invisible mass that is gravitationally contributing, but otherwise invisible. The other 70% is dark energy – a mysterious phenomenon that would explain why the expansion of the universe is accelerating rather than being slowed down by gravity.

The latest work uses data from the Dark Energy Survey, which has been probing the skies for six years from a mountaintop in Chile, and the South Pole Telescope, which is looking for faint traces of radiation crossing the sky from the first moments of the universe. . In both cases, the analysis uses a phenomenon called gravitational lensing, whereby light is slightly bent as it passes massive objects, such as galaxies and dark matter clusters, allowing scientists to infer the distribution of matter in the universe.

Separately, scientists can infer the structure of the very first universe from the heat left behind by the big bang and use computer models to “fast forward” and see if the models line up with observations.

Analysis indicates that the material is not as “clustered” as expected. According to Professor Carlos Frenk, a cosmologist at Durham University who was not involved in the research, there are three likely explanations. First, it could be the result of noise in the data or a systematic error in the telescope. It is also possible that, rather than a major rewrite of cosmological theory, a poorly understood astronomical phenomenon may explain the results. “For example, supermassive black holes at the center of galaxies can produce huge jets of radiation that can, in principle, move matter around and smooth it out a bit,” he said.

The third and most exciting option is that the discrepancy is explained by entirely new physics, such as the existence of new types of neutrinos, the exotic behavior of dark energy, or unconventional forms of dark matter. “Of the three possibilities, I hope it’s the last, I’m afraid it’s the second but I suspect it’s the first,” Frenk said.

The results are published in the journal Physical Review D.

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