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The most detailed map of dark matter in our universe is strangely smooth


DES is an attempt to image as many galaxies as possible as an alternative to dark matter mapping. The gravity of dark matter plays a strong role in controlling how these galaxies are distributed, so scientists can use these locations to infer where there is a higher density of dark matter. From August 2013 to January 2019, dozens of scientists gathered together to use the 4-meter Victor M. Blanco Telescope in Chile to survey the sky in the near infrared.

There are two types of lynchpins in map creation. The first is simply observing the location and distribution of galaxies throughout the universe. This arrangement leads scientists to where the largest concentrations of dark matter are.

The second is observing gravitational lensing, a phenomenon in which light emitted from galaxies is gravitationally stretched by dark matter as it moves through space, as if you were looking through a magnifying glass. Scientists use a gravitational lens to infer how much actual space is close to dark matter. The more distorted the light, the more lumpy the dark matter.

The latest results take into account the first three years of DES data, recording more than 226 million galaxies observed over 345 nights. “We are now able to map dark matter over a quarter of the Southern Hemisphere,” says Niall Jeffrey, a researcher from University College London and École Normale Superior in Paris and one of the leaders of the DES project.

The extent of the DES dark matter map of the sky so far, after the latest discoveries. Bright spots consist of the highest concentrations of dark matter, while darker areas indicate lower intensity.

Dark Energy Survey

In general, the data agree with the so-called Standard Model of cosmology, which assumes that the universe originated in the Big Bang, and the total mass and energy content is 95% of dark matter and dark energy. The new map gave scientists a more detailed look at some of the vast dark matter structures in the universe that would otherwise remain invisible to us. The brightest points on the map have the highest concentrations of dark matter, and they form clusters and halos around voids of very low density.

But some unexpected wrinkles appeared. “We found hints that the universe is smoother than expected,” Jeffrey says. “These hints also appear in other gravitational lens experiments.”

This is not what general relativity predicts, which indicates that dark matter should be more lumpy and less uniformly distributed. Authors write يكتب In one of 30 sheets After declaring that “although the evidence is by no means definitive, we may be starting to see hints of new physics.” For cosmologists, “this corresponds to the possibility of changing the laws of gravity as described by Einstein,” Jeffrey says.

Although the effects are massive, sluggish caution is critical, due to how little we actually know about dark matter (something we still observe directly). complex, our lens results would be misleading.”

In other words, there may be some strange explanations for the results that may have skewed the map of dark matter – perhaps in ways consistent with general relativity. That would be a huge relief to any astrophysicist whose entire work is based on Einstein’s being, well, right. And let’s not forget that general relativity has held up well Every other test that have been thrown at him over the years.

The results are already making waves, even with several DES data releases pending. “Astronomers are already using these maps to study the structures of the cosmic web and to better understand the relationship between galaxies and dark matter,” Jeffrey says. We may not have to wait long to see if the results are just a snapshot, or if a massive rewriting of our understanding of the universe is on the way.



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