Researchers in Spain and Portugal believe that the worst black hole collision ever observed was caused by the gravitational wave GW190521 recorded by LIGO and the Virgo probe last year. It may be even more mysterious: the merger of two boson stars. If confirmed, this will be the first evidence of the existence of these hypothetical objects that constitute one of the main candidate substances for these dark matter.
In September 2020, cooperate with the detector to carry out scientific cooperation Ligao In the U.S. and Virgo In Italy, they announced the discovery of confusing gravitational waves: GW190521.This signal is the same as Merger of two black holes They are respectively 85 and 66 times the mass of the sun, creating a new mass of 142 solar masses, which is the largest mass ever detected by gravitational waves.
This discovery broke the knowledge about the origin of black holes. In fact, it is considered the first of a new family: Medium mass black hole, Is a missing link between the mass of stars formed by the collapse of stars and the supermassive black holes hidden in the centers of galaxies like ours.
In addition, according to astrophysicists, the largest of the two merged black holes (having 85 solar masses) is not the result of star collapse, which brings a series of questions and possibilities to the origin of stars. All in all, GW190521 is a challenge to understand its origin and its meaning in our understanding of the life and death of stars.
In this complex panorama, a study published in the journal today Medical letter with From the leader Galician Institute of High Energy Physics (IGFAE, University of Santiago de Compostela-Galicia) and the University of Aveiro (Portugal) proposed the new origin of this mysterious signal: it comes from the fusion of two foreign objects, these objects are called Boson star.
A “dark” ultralight boson
These stars are hypothetical objects that constitute one of the main candidates for star formation. Dark matter, Which accounts for about 27% of all content in the universe.Assuming this kind of collision occurs, the research team can calculate the masses of the basic components of these stars, which is called Ultralight bosonBillion times lighter than electronics
The author compared GW190521 with computer simulations of the merger of boson stars and found that these interpretation data are slightly better than the analysis of LIGO and Virgo. The results indicate that the signal source will have characteristics different from those originally predicted.
One of the lead authors said: “We will no longer talk about black holes. This eliminates the problem of encountering forbidden black holes.” Juan Calderon Bustillo IGFAE, “And since the merger of boson stars is much weaker, we concluded that the distance occurred much closer than LIGO and Virgo estimated, which gives us greater mass, 250 solar mass For the black hole formed at the end; therefore, the fact that an intermediate-mass black hole was observed is still correct, although this black hole is now much heavier.”
“Boson stars are almost as compact as black holes, but unlike black holes, they lack the famous’non-return’ surface, namely Event horizon“, explained to another author, Nicholas Sanchis GulaHe is a postdoctoral researcher at the University of Aveiro and the Higher Technical Institute of the University of Lisbon.
He continued: “When they merged, they formed a supermassive star, which became unstable and collapsed into a black hole. The signal produced by this process is the same as that of LIGO and Virgo. It is the same as that normally used by us The so-called matter is different from ordinary stars, boson stars will be composed of Ultralight boson, Is one of the most reasonable theoretical candidates for dark matter as we know it.”
To their surprise, the research team found that although their analysis was aimed at “preferring” black hole collisions, they showed that boson stars are more likely to fuse, although there is no conclusion.
The co-author said: “Our analysis shows that both cases have similar possibilities, although boson stars are more likely.” JoséA.Font, From the University of Valencia. “This is very promising because the models we currently use for these mergers are very limited, and there is still a lot of room for improvement. Using a more complete model can reveal more evidence supporting boson stars and will also enable us Able to study more gravitational wave signals under this assumption”.
The basic components of dark matter
This group of authors emphasized that their method not only means that the first observation of boson stars has been achieved, but also means that their basic composition has been observed: ultralight bosons, which is one of many scientists’ proposals. A new type of particle, which is the basic element of matter.
Is also a co-author of the work, Carlos HerdeiroThe University of Aveiro added: “One of the most fascinating results is that we can Measure the mass of hypothetical “dark” particles And we probably ruled out the case where it is zero, such as the case of photons that make up photons. If this result is confirmed by future analysis of other gravitational waves, then our result will represent the basic composition of dark matter-the first observational evidence that has been sought for decades.
In addition to IGFAE and the Portuguese Center, researchers from the University of Valencia, Monash University in Australia and the Chinese University of Hong Kong have also collaborated on this “groundbreaking” study, which believes that the fusion of boson stars can explain this collision. The most massive black hole ever observed and proved the existence of dark matter.
Juan Calderón Bustillo et al. “The merger of GW190521 as a Proca star: the potential new vector boson is 8.7×10-13 eV”. Physical Wright Pastor, 2021.