Mohammed Abdullah, the first author of the study, said, “If the matter were spread evenly all over the universe, it would correspond equally to an average density of about six hydrogen atoms in space.” , A graduate student in the Department of Physics and Astronomy at the University of California Riverside, and the Department of Astronomy at the Egyptian National Research Institute of Astronomy and Geophysics.
“However, since we know that 80% of matter is actually dark matter, in fact, most of the matter in this case does not consist of hydrogen atoms, but rather a type of substance that cosmologists do not yet understand.”
A well-proven technique for determining the total amount of matter in the universe is to compare the number and mass of galaxy clusters per unit volume with predictions from numerical simulations.
Because present-day galaxy clusters have formed from matter that has collapsed under their own gravity for billions of years, the number of clusters observed at the present time is very sensitive to cosmological conditions and, in particular, the total of matter Quantity.
“The higher percentage will result in more groups,” Abdullah said.
“The ‘Goldilocks’ challenge for our team was to measure the number of groups and then determine which answer was ‘correct’.”
“But it is difficult to measure the mass of any galaxy cluster correctly because most of the matter is dark so we cannot see it with binoculars.”
To overcome this difficulty, Abdullah and his colleagues developed a cosmological tool, called galvite, to measure the mass of a galaxy cluster using the orbits of its member galaxies.
The researchers applied their tool to SDSS observations to create a list of 1,800 galaxy clusters.
They then compared data on 756 groups from their list with simulations.
By combining their measurements with people from other teams using different techniques, they were able to determine a best combined value, leading to the conclusion that the matter accounts for 31.5 up 1.3% of the total amount of total matter and energy in the universe.
“We have been successful in making one of the most accurate measurements made using the galaxy cluster technique,” said Professor Gillian Wilson, a researcher in the Department of Physics and Astronomy at the University of California’s Riverside.
“Furthermore, this is the first use of galaxy orbit technology that has achieved a value in agreement with those obtained by teams using non-cluster techniques such as cosmic microwave background anisotropies, baryon acoustic oscillations, type I supernovas, or gravitational lensing. Let’s use. ”
“A major advantage of using our Galvite galaxy orbit technique was that our team was able to determine a mass for each cluster individually instead of relying on indirect, statistical methods,” said Dr. Researcher, a researcher at Astronomer. Anatoly Clippin said. Department at New Mexico State University and Department of Astronomy at the University of Virginia.
Team results appear in Astrophysical Journal.
Mohammad H. Abdulla and others. 2020. Cosmological constraints on Cos Me and Cl 8 from cluster clustering using the GalWCat19 optical-spectroscopic SDSS catalog. Apj 901, 90; doi: 10.3847 / 1538-4357 / aba619
The article is based on a press release provided by the University of California Riverside.