Dark Energy Survey Physicists Open New Window on Dark Energy

Dark Energy Survey Physicists Open New Window on Dark Energy

A map of the sky showing the density of galaxies, galaxies and matter in the universe over the part of the sky observed by the Dark Energy Survey. The left panel shows the galaxy density in that part of the sky, while the middle panel shows the material density and the right side shows the galaxy density. Red areas are denser, and blue areas are less dense than average. Credit: Chun-Hao To / Stanford University, SLAC National Accelerator Laboratory

The universe is expanding at an increasing rate, and although no one is sure why, researchers from the Dark Energy Survey (DES) had at least one strategy to figure it out: they would take measurements of the distribution of matter, galaxies and galaxies to better understand what’s going on.

It was quite difficult to achieve the goal, but now a team led by researchers from the SLAC National Accelerator Laboratory of the Department of Energy, Stanford University and the University of Arizona has come up with a solution. Their analysis, published on April 6 in Physical overview letters, provides more accurate estimates of the average density of matter as well as the tendency to clump together – two important parameters that help physicists investigate the nature of dark matter and dark energy, the mysterious substances that make up the vast majority of the universe .

“This is one of the best limitations of one of the best datasets to date,” says Chun-Hao To, lead author of the new article and a graduate student at SLAC and Stanford, who works with Kavli Institute for Particle Astrophysics and Cosmology Director work. Risa Wechsler.

An early goal

When DES decided in 2013 to map an eighth of the sky, the goal was to collect four types of data: the distances to certain types of supernovae, or exploding stars; the distribution of matter in the universe; the distribution of galaxies; and the distribution of galaxies. Each one tells researchers something about how the universe evolved over time.

Ideally, scientists would combine all four data sources to improve their estimates, but there is a problem: the distribution of matter, galaxies, and galaxies are all closely related. If researchers do not consider these ratios, they will eventually ‘double count’, placing too much weight on some data and not enough on others, To says.

To handle all this information incorrectly, the University of Arizona astrophysicist Elisabeth Krause and colleagues developed a new model that could properly offset the compounds in the distribution of all three sizes: matter, galaxies, and galaxies. In doing so, they were able to make the very first analysis to properly combine all these diverse datasets to learn about dark matter and dark energy.

Estimation improves

Addition of the model in the DES analysis has two effects, To says. First, measurements of the distribution of matter, galaxies, and galaxies tend to introduce different kinds of errors. Combining all three measurements makes it easier to identify such errors, making the analysis more robust. Second, the three measurements differ in how sensitive they are to the average density of matter and its lumpiness. As a result, the combination of all three can improve the precision with which the DES can measure dark matter and dark energy.

In the new article, To, Krause, and colleagues applied their new methods to the first year of DES data and sharpened the accuracy of previous estimates for the density and awkwardness of matter.

Now that the team can include matter, galaxies and galaxy groups simultaneously in their analysis, the addition of supernova data will be relatively simple, as that kind of data is not as closely related to the other three, To says.

“The immediate next step,” he says, “is to apply the machinery to DES Year 3 data, which has three times greater air coverage.” It’s not as simple as it sounds: Although the basic idea is the same, the new data will require additional efforts to improve the model to keep up with the higher quality of the newer data, To says.

“This analysis is really exciting,” Wechsler said. ‘I expect it will set a new standard in the way we can analyze data and learn more about dark energy from large recordings, not only for DES, but also look forward to the incredible data we will get from the Vera Rubin Observatory’s Legacy Survey. of space and time in a few years. ‘


The smallest galaxies in our universe reveal dark matter


More information:
C. To et al, Dark Energy Survey Year 1 results: cosmological limitations of cluster abundance, poor lens and galaxy correlations, Physical overview letters (2021). DOI: 10.1103 / PhysRevLett.126.141301

Provided by SLAC National Accelerator Laboratory

Quotation: Dark Energy Survey Physicists Open New Window to Dark Energy (2021, April 6) Retrieved April 6, 2021 from https://phys.org/news/2021-04-dark-energy-survey-physicists-window.html

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