Monday , July 26 2021

A study by Japanese scientists rocked Stephen Hawking's dark matter theory.



One of the most famous theories about dark matter by Stephen Hawking was heavily shaken after the publication of the results of the Japanese astrophysical team led by Masahiro Takadas of the Institute of Physics and Mathematics of the Universe in Kabul, Live Science reports. A famous physicist who left this world last year believed that this mysterious and invisible substance consisted of primary black holes that appeared just after the Big Bang. Japanese scientists using the Subaru telescope have conducted an experiment, the results of which, although they do not completely contradict Hawking's theory, recognize that these black holes must be really small to explain the nature of the dark matter.

Dark matter is the term by which physicists call the mysterious substance which, in their view, can explain an interesting fact: everything in the universe moves and rotates as if it contains more mass than we can find. Different scientists at different times attempt to attribute the properties of so-called dark matter to different objects. In the 1970s, Stephen Hawking and his colleagues suggested that the Big Bang could create a large number of relatively small black holes, each with a proton size. These small celestial bodies are hard to see, but they will have a strong gravitational effect on other objects – two known properties of dark matter.

Until now, this theory could only be tested on primary black holes whose mass is larger than the lunar. But with advances in technology, scientists have been able to get clearer images of space. For a new study, a group of Japanese astronomers used the Hyper Suprime-Cam (HSC) camera mounted on the Subaru telescope in Hawaii. With her help, they shot the entire Andromeda, our closest galaxy, trying to find these small objects. The result of their work was published in the journal Nature Astronomy.

The black holes do not emit light, but the super massive black holes, like the one found in the center of the M87 galaxy, to which scientists have recently taken a picture, are surrounded by bright hot-discs. But since the primary openings are billions of times smaller and have no visible light that surrounds them, they can only be detected by observing the powerful gravitational fields created by them, resulting in distortion of the radiation of adjacent objects. This phenomenon is called micro-healing.

Telescopes are able to detect the micro-lance with a black hole with a long shot of stars. When the black gift passes in front of the observation point and the star, it distorts the light of the star, causing it to blink. The smaller the black hole, the faster the flash gets.

"If an object that creates microwaves has, say, a solar mass, then the time scale (flash duration) will be from a few months to a year," explains Masahiro Takadas of the Institute of Physics and Mathematics of the Universe in Kabul.

However, the primary holes the Japanese team was looking for had only a fraction of that mass – it was approximately equal to the mass of our Moon. This means that the observed lightning strikes must be much shorter.

Taka called the HSC camera unique because scientists managed to get images of all the stars of the Andromeda galaxy with a minimum shutter speed of about 2 minutes. As a whole, astronomers managed to get about 200 Andromeda shots for 7 hours of clear night. As a result, they found only one suspicious event for micro-lanes. According to Takada, if the primary black holes represent much of the dark matter, then they must have seen about 1000 micrograms of signal.

"Microlensing is the gold standard of black hole detection technology," said Simeon Byrd of the University of California, who studies black holes but did not participate in the latest study.

"The work of Japanese scientists allows us to exclude primary black holes as a major source of dark matter."

Does that mean that Hawking's theory is totally disproved? Taka and Bird are in no hurry to make definitive conclusions. According to them, the results obtained can not yet completely exclude the existence of primary black holes because, due to their small mass, the flashes of their signals would be too short to capture them. Researchers believe it is necessary to develop new tools to enable them to be discovered.

At the same time, scientists note that detecting even one such signal may be crucial for further research, which will be a revolutionary test of some Hawking theories.

"Only one observation can not convince us of anything. It is necessary to carry out additional. If this signal was really a signal for the first black hole, we need to continue the search for its relatives, "Takada concludes.

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