April 13, 2024

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Study of X-rays of the sky relieves cosmic tension

Study of X-rays of the sky relieves cosmic tension

New analysis of How do galaxy clusters evolve? Over time, precise measurements were obtained of the total amount of matter in the universe and the degree of its clumping.

These and other results They were reported in a series of articles published by scientists Of the German consortium eROSITA, led by the Max Planck Institute for Extraterrestrial Physics.

The results relieve tension between Previous congestion measurementsproviding insights into elusive measurements of neutrino mass and pressure provided by dark energy.

Two weeks ago, the German consortium eROSITA Published data from the first sky study. The main goal of the study is to better understand cosmology by measuring the assembly of galaxy clusters over cosmic time, some of the largest structures in our universe. By tracking the evolution of the clusters through X-rays emitted by the hot gas, EROSITA has made precise measurements of both the total amount of matter in the universe and its clumping. The eROSITA measurements resolve previous discrepancies between previous mass measurements using different techniques, namely the cosmic microwave background (CMB) and weak gravitational lensing.

“eROSITA has now measured the evolution of cumulonimbus clouds “The cosmological parameters we measure in galaxy clusters are a tool for next-level precision cosmology,” said Dr. Israa Bulbul (MPE), lead scientist on the eROSITA cosmology and cluster team that provided the groundbreaking results, in a statement. It matches the latest CMB technology, showing that the same cosmological model has persisted from shortly after the Big Bang until today.

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Matter of all kinds constitutes 29% of the energy density of the universe

According to the standard cosmological model called Lambda model of cold dark matter (Lambda-CDM), the underlying universe was an extremely dense and hot sea of ​​photons and particles. Over cosmic time, small differences in density grew into the large galaxies and galaxy clusters we can see today. The eROSITA group's feedback shows this Matter of all types (visible and dark) currently makes up 29% of density energy The total universe, in excellent agreement with values ​​obtained from measurements of the cosmic microwave background radiation, which was emitted when the universe first became transparent.

In addition to measuring the overall density of the material, eROSITA also measured the clumping of the material's distribution, using a parameter called S8. An important advance in cosmology in recent years has been the so-called “S8 tension.” This tension arises because cosmic microwave background experiments measure a higher value of S8 than, for example, cosmological studies with weak gravitational lensing.

a New physics is implied unless this tension is resolvedeROSITA has done just that. “Erosita tells us that the universe has behaved as expected throughout cosmic history,” says Dr. Vittorio Gherardini, a postdoctoral researcher at MPE who led the cosmology study. “There's no tension with the CMB, and maybe now cosmologists can relax a little.”

Undetectable molecules

The largest structures in the universe also contain information about the smallest particles – neutrinos. These light particles are almost impossible to detect. “It may seem contradictory, but we get it Strict constraints on the mass of the lightest known molecules are abundant “One of the largest objects in the universe,” Gherardini said. Although neutrinos are small, they are “hot,” meaning they travel at nearly the speed of light. Therefore, they tend to facilitate the distribution of matter, which can be verified by analyzing the evolution of galaxy clusters in the universe.

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“We are even on the verge of a breakthrough To measure the total mass of the combined neutrinos “With ground-based neutrino experiments,” Gherardini adds. The group evolution in the eROSITA data alone indicates an upper limit on the total mass of 0.22 eV (eV); With the CMB data, this is reduced to 0.11 eV at a 95% confidence level, and this is the most accurate combined measurement to date by any observational cosmology probe.