One of the most famous theories of Stephen Hawking aboutdark matter strongly shaken after the publication of the results of the Japanese team of astrophysicists under the leadership of Masahiro Takada from the Physics and Mathematics Institute of the Universe in Kavli, reports Live Science. A famous physicist who left this world last year believed that this mysterious and invisible substance consists of primary black holes that appeared immediately after the Big Bang. Japanese scientists using the Subaru telescope conducted an experiment, the results of which, although they do not completely refute the Hawking theory, they admit that these black holes must be really tiny to explain the nature of dark matter.
Dark matter is a term by which physiciststhey called this mysterious substance, which, in their opinion, could explain one interesting fact: in the Universe everything moves and rotates as if there were more mass in it than we are able to detect. Different scientists at different times tried to attribute the properties of the 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 the size of a proton. These tiny celestial bodies are difficult 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 verifiedon the primary black holes, the mass of which is greater than the lunar. But with the development of technology, scientists were able to obtain more and more clear images of outer space. For their new study, a group of Japanese astronomers used the Hyper Suprime-Cam (HSC) camera mounted on a Subaru telescope in Hawaii. With her help, they took pictures of the entire Andromeda, the nearest galaxy to us, trying to find these small objects. The result of their work was published in the journal Nature Astronomy.
Black holes do not emit light, howeversupermassive black holes, like the one in the center of the galaxy M87, which scientists recently obtained a photo of, are surrounded by bright accretion disks of hot matter. But since the primary holes are billions of times smaller and have no visible luminous matter surrounding them, they can only be found by observing the powerful gravitational fields created by them, causing distortion of the radiation of neighboring objects. This phenomenon is called microlensing.
Telescopes are able to detect black microlensesholes with the help of long shooting stars. When a black gift passes in front of the observation point and the star, it distorts the light of the star, causing it to “flash”. The smaller the black hole, the faster this flash occurs.
"If the object that creates the microlens hassay, one solar mass, then the time scale (the duration of the outbreak) will be from several months to a year, ”explains Masahiro Takada from the Physics and Mathematics Institute of the Universe in Kavli.
However, the primary holes that the Japanese team was looking for possess only a fraction of this mass - it is approximately equal to the mass of our Moon. This means that the observed flashes should be much shorter.
Takada calls the HSC camera unique becausewith the help of it, scientists were able to at once obtain images of all the stars of the Andromed galaxy with a minimum exposure time of about 2 minutes. In total, astronomers were able to get about 200 pictures of Andromeda for 7 hours of a clear night. As a result, they found only one suspected microlensing event. According to Takada, if the primary black holes account for a large proportion of dark matter, then they should have seen about 1000 microlensing signals.
“Microlensing is the gold standardtechnology to search for black holes, ”says physicist Simeon Bird 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 the main source of dark matter."
Does this mean that Hawking's theory wascompletely refuted? Takada and Byrd do not rush to final conclusions. According to them, the results obtained cannot yet completely exclude the existence of primary black holes, since, due to their small mass, the flashes of their signals would be too short to catch them. According to researchers, it is necessary to develop new tools that would allow them to be detected.
At the same time, scientists note that the discovery of even one such signal may be crucial for subsequent research, which will be a revolutionary test of some Hawking theories.
“Only one observation cannotto convince us of something. It is necessary to conduct additional. If this signal was indeed the signal of the primary black hole, we must continue the search for its relatives, ”concludes Takada.
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