Missing barions found in the farthest parts of galactic rays

Scientists channeled the universe – a relic of the formation of the universe known as the cosmic microwave background (CMB) – to solve a mystery about missing matter and learn new things about galaxies. Their work can also help us better understand dark energy and test Einstein’s general theory of relativity by providing new details about the rate at which galaxies move toward or away from us.

Invisible dark matter and dark energy account for about 95% of the total mass and energy of the universe, and the majority of the 5% considered ordinary matter is also largely unseen, as are the gases on the outskirts of galaxies from which they exist; called a halo.

Most of this ordinary matter is made up of neutrons and protons – particles called barions and are made up of nuclei such as hydrogen and helium. Only about 10% of baronic matter is in the form of stars, and most of the rest occupy the space between galaxies in strings of hot, dispersed matter known as the hot intergalactic medium, or WHIM.

Because barions are so widely distributed in space, it has been difficult for scientists to get a clear picture of their location and density around galaxies. Because of this incomplete picture of where ordinary matter is, most of the universe’s barions can be considered ‘missing’.

Now an international team of researchers, with significant contributions from physicists from the U.S. Department of Energy, Lawrence Berkeley National Laboratory (Berkeley Lab) and Cornell University, have mapped the location of these missing barions by giving the best measurements so far of their location. and density around groups of galaxies.

It appears that the barions occur in galaxies, and that these ray circles extend far beyond what popular models predicted. Although most stars of an individual galaxy are usually located in an area about 100,000 light-years from the galaxy, these measurements show that the farthest barions for a given group of galaxies are about 6 million light-years from their center.

Paradoxically, this missing matter is even more difficult to map than dark matter, which we can observe indirectly through its gravitational effects on normal matter. Dark matter is the unknown that makes up about 27% of the universe; and dark energy, which drives matter in the universe at an accelerated rate, makes up about 68% of the universe.

“Only a few percent ordinary matter is in the form of stars. Most are in the form of gas that is generally too faint, too diffuse to detect,” said Emmanuel Schaan, Chamberlain Postdoctoral Fellow at Berkeley Labs Physics , said. Section and lead author for one of the two articles on the missing barions, published on March 15 in the magazine Physical overview D.

The researchers used a process known as the Sunyaev-Zel’dovich effect, which explains how CMB electrons get a boost in energy through a scattering process, as they interact with hot gases around galaxies.

“It’s a great opportunity to look beyond galaxy positions and galaxy velocities,” said Simone Ferraro, a Berkeley Lab physics division member who participated in both studies. “Our measurements contain a lot of cosmological information about how fast these galaxies are moving. It will complement the measurements that other observatories are doing and make them even more powerful,” he said.

A team of researchers at Cornell University consists of research fellow Stefania Amodeo, assistant professor. Professor Nicholas Battaglia, and graduate student Emily Moser, led the modeling and interpretation of the measurements and investigated the consequences for poor gravity lensing and galaxy formation.

The computer algorithms developed by the researchers should be useful for analyzing data with a poor lens recording of future experiments with high precision. Lens phenomena occur when massive objects such as galaxies and galaxies are directed in a specific line approximately, so that the gravitational distortion further bends and distorts the light of the object.

Poor lens formation is one of the most important techniques that scientists use to understand the origin and evolution of the universe, including the study of dark matter and dark energy. The study of the location and distribution of baronic material brings these data within reach.

“These measurements have complex implications for poor lenses, and we expect this technique to be very effective in calibrating future examinations with poor lenses,” Ferraro said.

Schaan commented: “We also get information that is relevant to the formation of galaxies.”

In recent studies, researchers have relied on a data system from the Milky Way systems of the ground-based Baryon Oscillation Spectroscopic Survey (BOSS) in New Mexico, and CMB data from the Atacama Cosmology Telescope (ACT) in Chile and the space-based Planck. telescope of the European Space Agency. . Berkeley Lab has played a leading role in the BOSS mapping effort and developed the computational architectures needed for the processing of Planck at NERSC.

The algorithms they created benefit from the analysis using the Cori supercomputer in the Berkeley Lab’s DOE-funded National Energy Research Scientific Computing Center (NERSC). The algorithms counted electrons so that they could ignore the chemical composition of the gases.

“It’s like a watermark on a banknote,” Schaan explained. “When you place it in front of a taillight, the watermark appears as a shadow. For us, the background is the cosmic microwave background. It serves to illuminate the gas from behind so that we can see the shadow as the CMB light through it. move. gas. ‘

Ferraro said: “This is the first measurement with a very important meaning that really captures where the gas was.”

The new image of galaxies presented by the software “ThumbStack” created by researchers: massive, vague spherical regions that extend far beyond the starlight regions. This software is effective at mapping the ray charts, even for groups of galaxies with low mass radiation and for those that move away from us very quickly (known as ‘high-red-shift’).

New experiments that could benefit from the halo mapping instrument include the Dark Energy Spectroscopic Instrument, the Vera Rubin Observatory, the Nancy Grace Roman Space Telescope, and the Euclid Space Telescope.