Home Tech The unexplainable double black hole merger last year may actually be a double boson star merger composed of dark matter | TechNews Technology News

The unexplainable double black hole merger last year may actually be a double boson star merger composed of dark matter | TechNews Technology News

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Last year, scientists discovered GW190521, the largest gravitational wave event in the history of the merger of two black holes. The mass of the new black hole after the merger is as high as 142 times the mass of the sun. However, according to new research conclusions, in fact, this may not be a double black hole collision, but a merger of two boson stars.

At present, the black holes we have discovered can only be classified into two categories: one is a stellar black hole with a mass between 5 to tens of times the mass of the sun; the other is a supermassive black hole with a mass of millions or even billions of times that of the sun. . A “blank zone” is formed between stellar black holes and supermassive black holes. Scientists cannot find black holes whose mass falls in this gap. They can only assume that there are intermediate mass black holes (IMBH) lurking in this zone with masses ranging from 100 to 100. Between 10,000 solar masses.

Although some clues to intermediate-mass black holes have been discovered in the past, the evidence for their existence remains to be confirmed. In September last year, LIGO and Vergo announced the gravitational wave signal GW190521. According to analysis, this signal came from two black holes with a mass of 85 and 66 times the sun. The two merged to form a new black hole with a mass of 142 times the sun. It was the first medium-mass black hole to be confirmed.

However, this observation also poses a huge challenge to existing stellar evolution models. If the current theory of star birth and death is correct, then it is impossible for a star to form a black hole of up to 85 solar masses when it collapses at the end of its life. How to explain the existence of this celestial body 85 times the mass of the sun?

Recently, an international team from the Institute of High Energy Physics of Galicia (IGFAE), the University of Aveiro in Portugal, the Advanced Institute of Technology of the University of Lisbon, the University of Valencia in Spain and the Monash University in Australia proposed a new source of the GW190521 signal. Object: Double Boson Star.

A strange boson star that may be made of dark matter

In the analysis of the new paper, the particles that make up these stars (the ultralight bosons) are billions of times smaller than electrons.

The boson star is still an imaginary celestial body, and it is also the simplest one among many imaginary strange stars. Compared with ordinary stars, which are mainly composed of fermions, boson stars are composed of stable and self-repelling bosons. , And the constituent matter is probably the hypothetical dark matter particle axion (Axion).

Therefore, compared with ordinary stars that emit light due to gravity and nuclear fusion, boson stars are theoretically invisible and difficult to detect. In essence, boson stars act like black holes, with strong gravitational pull from the surrounding environment. Absorbing matter and bending the path of light is similar to the situation near the event horizon of a black hole. The difference between the two is that light cannot escape from the black hole, but boson stars do not have this problem, at most we can’t see it.

Researchers simulated the merging process of boson stars and found that they would produce a signal consistent with the GW190521 event. In other words, double boson stars can explain the origin of intermediate-mass black holes more reasonably than double black holes.

The team pointed out that because the merger process of boson stars is much weaker than the merger of black holes, the calculated distance is also closer than the original estimate, which will also cause the final mass of the black hole to become larger, about 250 suns. The mass still falls within the range of a medium-mass black hole, but it can solve the problem that the original black hole exceeds the theoretical upper limit.

This is likely to be the first evidence of the discovery of a boson star, but it is not yet certain. If this research is rigorously reviewed and confirmed, the achievements will go far beyond the discovery of new celestial bodies, and it will help unlock the universe. One of the most puzzling mysteries in science-dark matter, that is, the existence of axons.

The new paper was published in “Physical Review Letters” (Physical Review Letters).

(Source of the first image: IGFAE)

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