New turn in the history of dark matter

New turn in the history of dark matter

Innovative rethinking of X-ray information from galactic clusters will help clarify the nature of dark matter. For this purpose, the Chandra X-ray observatory, XMM-Newton and Hitomi were used. If their data are confirmed by future observations, then we will be able to understand the mysterious invisible substance that fills 85% of the matter of the Universe.

The study began in 2014, when astronomers recorded a surge in intensity with extremely specific energy in the Perseus galactic cluster. This emission line has an energy of 3.5 keV. This intensity was difficult to explain in terms of familiar objects, therefore, they suggested the existence of dark matter. Later, 73 other galactic clusters were investigated and the same results were found. After 2 weeks, another team of scientists came to the same conclusion.

A quick look at the Perseus Cluster

But these two results remained controversial: someone found the 3.5 keV line, while others did not. The debate ended in 2016 with the advent of Hitomi, designed to search for such features. So this telescope could not find the 3.5 keV line in Persey. But here the story makes a sharp turn.

Some scholars noted that the image of Hitomi was much more bizarre than Chandra showed. It turned out that the Perseus data is represented by a mixture of X-ray signals from two sources: the diffuse component of the hot gas that engulfed the galactic center, and the X-rays near the supermassive black hole. When using Chandra, it was possible to separate these sources and reveal an excess of X-rays at 3.5 keV. Hence the need to explain this behavior: the detection of X-ray absorption in the survey of a black hole and the emission of rays at the same energy, but already in the survey of a hot gas.

The latest data show that X-ray absorption at 3.5 keV is detected in the region around the black hole in the center of Perseus. This means that the particles of dark matter in the cluster absorb and release the radiation. If the new model is true, then one day it will help determine the true nature of dark matter.

This behavior is familiar to scientists studying stars and gas clouds using optical telescopes. Starlight often exhibits absorption lines. Absorption removes atoms from low to high energy state. An atom quickly goes to low energy and releases light. If we only follow the cloud in the direction from the star, then only a fluorescent light would be found.

The researchers believe that dark matter particles can behave like atoms with two energy states separated by 3.5 keV. To learn new details, scientists will have to continue to observe the cluster of Perseus and the like.

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