California, United States
The scientists operating the LIGO and Virgo detectors announced to have detected the largest source of gravitational waves recorded so far and they admitted that their finding actually raises more questions than answers.
This was considered by Alan Weinstein, member of LIGO (Laser Interferometry Gravitational Wave Observatory) and professor of physics at the California Institute of Technology (Caltech), when presenting the finding.
A gravitational wave is a invisible wave moving at the speed of light. Albert Einstein postulated its existence as early as 1915, as part of the theory of general relativity, but the phenomenon was only experimentally detected in 2015 precisely through LIGO.
They are difficult to detect and both LIGO and Virgo (an observatory located near Pisa, Italy, in which the host country plus France, Spain, the Netherlands, Poland and Hungary participate) were created especially for it; The finding reported on Wednesday may have been the most important to date.
Weinstein added about the discovery that for the moment he opts to give him the simplest explanation, which is to attribute the emergence of gravitational waves to the fusion of two black holes binaries.
“The bar to say that we have discovered something new is very high. So we usually apply Occam’s razor: the simplest solution is the best, which in this case is a black hole binary, “he added.
However, scientists do not hide that the size of the find is something unprecedented and that the signal that was detected was much stronger than on the other occasions in which they could be traced. gravitational waves.
“This is not much like a screech, which is what we normally detect,” Virgo member Nelson Christensen, a researcher at the French National Center for Scientific Research (CNRS) said Wednesday.
The gravitational waves detected and of which details are now given were developed, according to the scientists, an energy similar to that of eight solar masses.
The signal was detected on May 21, 2019 by LIGO, which is made up of two observatories located in the United States, and by Virgo in Italy, and has been assigned the identification GW190521.
It resembles about four short movements, and is extremely short in duration, less than a tenth of a second, the scientists explained.
That indicates, according to the researchers, that GW190521 was generated by a source that is approximately 5 gigaparsecs away, when the universe was about half its current age, making it one of the most distant detected so far.
The gigaparsec is an astronomical measurement that is roughly equivalent to 3.26 billion light years.
Almost all the gravitational wave signals confirmed to date come from a binary merger, either between two black holes or two neutron stars, so that is the first hypothesis that scientists consider, who believe they are facing the largest merger. between two black holes with masses 85 and 66 times the mass of the sun.
The new signal likely comes from the instant the two black holes merged. The merger created an even larger black hole, about 142 solar masses, and released an enormous amount of energy, equivalent to about 8 solar masses, scattered throughout the universe in the form of gravitational waves.
The international team of scientists reported their findings in two articles published Wednesday.
One, which appears in Physical Review Letters, details the discovery, and the other, in The Astrophysical Journal Letters, discusses the signal’s physical properties and astrophysical implications.
The exceptionally large masses of the two original black holes as well as the final black hole raise a host of questions about their formation.
All black holes observed to date fit into one of two categories: on the one hand, black holes ranging from a few solar masses to dozens of solar masses have been detected and are believed to form when stars die.
On the other hand, supermassive black holes have been found, such as the one in the center of the Milky Way, measuring hundreds of thousands to billions of times that of our sun.
However, the latest 142-solar-mass black hole produced by the GW190521 merger falls within an intermediate mass range between stellar and supermassive black holes, the first of its kind ever detected.
The two black holes that produced the final black hole also appear to be unique in size. They are so large that scientists suspect that one or both may not have formed from a collapsing star, as is the case with most stellar-mass black holes.
In any case, that is something that would call into question part of the current theories of stellar evolution that may have to be rewritten.
“The fact that we are seeing black holes of these dimensions will make many astrophysicists scratch their heads and try to find out how they were produced,” said Christensen.EFE