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The average temperature of gas across the Universe has increased more than 10 times over the past 10 billion years and has reached around 2 million Kelvin today, according to a new study published in the Astrophysics Journal.
As the Universe evolves, concentrations of matter are surrounded by increasingly hot gas halos. Image Credit: D. Nelson / Illustris Collaboration.
“Our new measurement provides direct confirmation of the founding work of Jim Peebles, who laid out the theory of large-scale structure formation in the Universe,” said lead author Dr. Yi-Kuan Chiang, researcher at the Center for Cosmology and Astro Particle Physics at Ohio State University.
The large-scale structure of the Universe refers to global models of galaxies and clusters of galaxies on scales beyond individual galaxies. It is formed by the gravitational collapse of dark matter and gas.
“As the Universe evolves, gravity brings together dark matter and gas from space into galaxies and clusters of galaxies. The trail is violent – so violent that more and more of the gases are electrocuted and heated, ”Dr Chiang said.
“The results showed scientists how to synchronize the progress of the formation of the cosmic structure by ‘checking the temperature’ of the Universe.”
Dr Chiang and his colleagues used a new method which allowed them to estimate the temperature of gas farther from Earth – meaning further in time – and compare them to gases closer to Earth and close to the present time.
Using data collected by ESA’s Planck satellite and the Sloan Digital Sky Survey, they estimated the redshift of gas concentrations observed in microwave light images going back in time to 10 billion ago. years.
They discovered that gases in the present universe reach temperatures of around 2 million Kelvin around objects closer to Earth. This is about 10 times the temperature of the gases around objects farther away and further away in time.
This trend is also predicted by numerical simulations showing how dark matter and atoms in gas evolve over time.
“The Universe is heating up because of the natural process of formation of galaxies and structures,” Dr. Chiang said.
“It has nothing to do with global warming. These phenomena occur on very different scales. They are not connected at all. “
“We have measured temperatures throughout the history of the Universe,” said co-author Professor Brice Ménard, a researcher at the Kavli Institute for the Physics and Mathematics of the Universe and the Department of Physics and Mathematics of the Universe. astronomy from Johns Hopkins University.
“Over time, all of these galaxy clusters get hotter and hotter because their gravity pulls more and more gas towards them.
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Yi-Kuan Chiang et al. 2020. Cosmic thermal history probed by Sunyaev-Zeldovich effect tomography. ApJ 902, 56; doi: 10.3847 / 1538-4357 / abb403
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