Researchers measure 12,000 constellations | SN.at

An analysis of data from the German telescope “Erosita” has incredible numbers to offer: sky surveys revealed evidence of a total of 12,247 X-ray galaxy clusters. At least 8,361 of them are new discoveries, the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching said on Wednesday. The new calculations, in which experts from the University of Innsbruck were also involved, surprisingly match the previous assumptions.

“eRosita” (Extended Roentgen Survey with Imaging Telescope Array) makes visible large structures in space by detecting X-rays. It has been in space since 2019. It is mounted on the German-Russian “Spektr-RG” satellite. The focus of binocular observations is on constellations. These are structures of gigantic proportions: they are “clusters” of thousands of individual galaxies bound together by gravity.

“We knew from previous studies that these clusters should exist,” said Sebastian Grandis, who is part of the “Erosita” consortium and is from the team of Tim Schrapbach at the Institute of Astro and Particle Physics at the University of Innsbruck. liberation “With Erosita, we specifically looked for it. What's important here is that the plasma in galaxies emits X-rays because the temperature there is incredibly high — about ten million degrees Celsius.”

The radiation information is used to determine the distribution of galaxy clusters and approximately 1,300 “supercluster systems” in space. This distribution can be used to determine how the universe expanded after the Big Bang. This expansion is largely determined by the mysterious dark energy.

The mass of mega-structures billions of light-years away can also be inferred using the “gravitational lensing effect”. “We analyze the shape of the galaxies behind the clusters. These appear distorted because the light from the background galaxies in our path is deflected by the gravitational pull of the clusters. We can estimate this using Einstein's general theory of relativity. The mass that caused this distortion is the following: more mass , strong decay,” said Grandis, who carried out part of these calculations with the Tyrolean team, which was also based on measurement data from other observations by international teams. .

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The scientists compared the eRosita data to the standard model of cosmology — the “Lambda Cold Dark Matter” model — with assumptions about the nature of the universe. The new data's conclusion that the universe consists of a total of 29 percent visible and dark matter is “in excellent agreement with values ​​from measurements of the cosmic microwave background radiation from the early days of the universe,” says MPE. The striking agreement is that “the same cosmological model applies from shortly after the Big Bang to today,” says eRosita team leader Ezra Bulbul.

According to the model, “dark energy,” not yet understood by science, is responsible for the remaining 71 percent. Albert Einstein once incorporated it into the model as the “cosmological constant” – and then removed it again. “Our calculations show that Einstein was right, and then he was wrong to reject the cosmological constant,” Grandis said.

However, the data now recorded on the rate at which giant structures grow do not entirely match the predictions of general relativity. Based on this paradox, one “could be on the brink of a new discovery,” says MPE researcher Emmanuel Ortiz.

Based on the information from the telescope, new insights into tiny neutrinos can also be gained. These free-flying particles in space have so far largely escaped direct scientific observation. “Combined with other observational methods, our analysis makes it possible to obtain more precise results for the possible mass range of neutrinos,” Grandis says. According to MPE information, their total mass should not exceed 0.22 electron volts.

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While the consortium hopes to gain some insights into space from further analysis of the complete data set, a question mark hovers over Erosita's future: after the termination of cooperation with the Russian space agency Roscosmos in February 2022, the telescope is in “safe” mode, as announced by the University of Innsbruck. Therefore, the data only extends to 2022.

(Service – Releases on preprint servers: https://arxiv.org/pdf/2402.08458.pdf, https://arxiv.org/abs/2402.08455 And https://arxiv.org/abs/2402.08456; Current publication on “eRosita” data in “Astronomy & Astrophysics” journal: https://doi.org/10.1051/0004-6361/202347165)

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