The most detailed dark matter map of our universe is surprisingly smooth

DES strives to image as many galaxies as possible as a proxy for mapping dark matter. This is possible because the gravity of dark matter plays an important role in controlling the distribution of these galaxies. From August 2013 to January 2019, dozens of scientists gathered together and used Chile’s 4-meter Victor M. Blanco telescope to observe the near-infrared sky.

There are two keys to creating a map. The first is to simply observe the location and distribution of galaxies throughout the universe. This arrangement provides scientists with clues to the location of the largest dark matter concentration.

The second is to observe the gravitational lensing effect, that is, the phenomenon in which the light emitted by a galaxy is stretched by the gravitational force of dark matter as it passes through space. The effect is similar to viewing through a magnifying glass. Scientists use gravitational lensing to infer how much space is actually occupied near dark matter. The more the light is distorted, the more the dark matter clumps.

The latest results take into account the DES data of the previous three years and count more than 226 million galaxies observed in 345 nights. “We are now able to map out a quarter of the dark matter in the southern hemisphere,” said Niall Jeffrey, a researcher from University College London and École Normale Supérieure in Paris, who is one of the leaders of the DES project.

In general, these data are consistent with the so-called standard model of cosmology, which assumes that the universe was created in the Big Bang and its total mass energy content is 95% dark matter and dark energy. This new map provides scientists with a more detailed view of some of the huge dark matter structures in the universe, otherwise we would not be able to see these structures. The brightest points on the map represent the highest concentration of dark matter, and they form clusters and halos around very low-density voids.

But some results are surprising. “We found signs that the universe was smoother than expected,” Jeffrey said. “These hints can also be seen in other gravitational lens experiments.”

This is not predicted by general relativity, which suggests that dark matter should be more clumped and distributed more unevenly.The author wrote In one of 30 papers Released “Although the evidence is by no means certain, we may begin to see signs of new physics.” For cosmologists, “this may change the law of universal gravitation described by Einstein,” Jeffrey said.

Although the impact is huge, caution is the most important, because we actually know very little about dark matter (something we haven’t directly observed). For example, Jeffrey pointed out, “If nearby galaxies are arranged in strange ways due to complex astrophysics, then our lens results will be misled.”

In other words, the results are likely to have some strange explanations—perhaps they were explained in a way consistent with general relativity. For any astrophysicist whose life’s work is based on Einstein being correct, this would be a huge relief.Let us not forget: the general theory of relativity has been proved very well Every other test Has been tossed aside for many years.

The results have caused a stir, even if there are more DES data yet to be released. “Astronomers are already using these maps to study the structure of the cosmic web and to better understand the connection between galaxies and dark matter,” Jeffrey said. We may not have to wait too long to find out whether the results are really short-lived, or our understanding of the universe needs a lot of rewriting.