New map shows how dark matter ‘connects’ major galaxies


Dark matter is one of the most enduring mysteries in the universe. Its existence can be intuitively discerned by how it affects gravity, yet no one knows exactly what it is, even though it accounts for 27% of the universe’s total mass and energy—much more than 5% of the universe’s “ordinary” matter, such as planets and stars, Include.

However, although they don’t know what kind of particles make up dark matter, astronomers have been able to use telescopes to guess where dark matter is in the universe. This is largely due, true to its name, to the difficulty of observing dark matter directly, but it has an enormous gravitational effect and a large mass wherever it appears loose.

Astronomers are now using this data to create a detailed map of the dark matter in the universe.

First, astronomers at the University of Waterloo published a study four years ago in Monthly Notices from the Royal Astronomical Society Map of dark matter filaments extending between galaxies. Then recently, a team of international researchers published a new map that was published in Astrophysical Journal مجلة.

Dark matter maps usually contain galaxies very far from our Local Super Cluster, the neighborhood of gravitationally bound galaxies that includes the Milky Way.

“Ironically, it is easier to study the distribution of dark matter much further because it reflects a past so far away, which is much less complex,” said Donghui Jeong, associate professor of astronomy and astrophysics at Pennsylvania State University. Advertising.

Jeong was referring to the fact that observing a distant galaxy means, by definition, observing something that happened a long time ago due to the low speed of light. “Over time, as the large-scale structure of the universe has evolved, the complexity of the universe has increased, so it is inherently difficult to make measurements on dark matter locally.”

Previous attempts to map dark matter have been cumbersome. In their latest efforts, the researchers relied on a large number of galactic simulations, called Illustris-TNG, which included galaxies, gases, and other visible matter in addition to dark matter. Galaxies similar to the Milky Way were specifically selected in the simulations; In particular, data for 17,000 galaxies located within 650 million light-years of the Milky Way. The researchers relied on machine learning to put them together and achieve a noble result.

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“When given certain information, the model can fill in the gaps based on what it looked at before,” Jeong said. “The map of our models doesn’t quite match the simulated data, but we can still reconstruct very detailed structures. We found that the inclusion of the motion of galaxies—their own radial velocities—as well as their distribution is greatly improved. The quality of the map allowed us to see these details.

In fact, the quality of the map is far superior to that created in the past. As Jeong said, the new simulation improves on the small details. Specifically, the map highlights the structures of the extragalactic region known as the “Local Sheet” and “Local Mass,” both of which comprise parts of our Milky Way. It also identifies new structures that astronomers will study more. Remarkably, the map also details the directional “flow” of dark matter, as indicated by the arrows.

“Having a local map of the cosmic web opens a new chapter in cosmological study,” Jeong said. “We can study the relationship between the distribution of dark matter and other emission data, which will help us understand the nature of dark matter. And we can directly study these filamentous structures, these hidden bridges between galaxies.”

Jeong stressed that a better understanding of the role of dark matter in our universe is essential to our current and future existence.

“Because dark matter dominates the dynamics of the universe, it fundamentally determines our destiny,” Jeong said. “So we can ask a computer to develop the map for billions of years to see what will happen in the local universe. And we can evolve the model over time to understand the history of our cosmic neighborhood.”

Map preview can be found Here.


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