Thanks to the interferometers Ligo and Virgo, the two most important gravitational wave detectors here on Earth, a very powerful union was recently discovered between two “anomalous” black holes, seven billion light years away.
The research conducted using the data collected by the two interferometers has something sensational: not only have several records been broken, but it also shows further confirmation of the existence of the elusive intermediate-class black holes, a collection of cosmic monsters ranging from a few hundred to millions of solar masses, of which still existence it was not possible to give an explanation definitive.
The research team found a very violent union between two black holes, respectively of 66 and 85 solar masses, about 7 billion light years away from the earth. In practice, the merger between the two cosmic monsters took place when our universe was half its years old. This suggests how intense the signal Gw 190521 (so called by the researchers) that has come down to us, recorded by interferometers on May 21, 2019, for only 0.1 seconds. The merger of the two black holes gave birth to another devourer of matter of 142 solar masses – a record for the interferometric observation of Ligo and Virgo.
What intrigued the researchers most, as evidenced by the double publication of two consequential studies – the first in the Physical Review Letters and the second in the Astrophysical Journal Letters, was the black hole progenitor of 85 solar masses: according to what is stated by the models modern cosmologicals a black hole of such proportions could not have been born from a simple collapse of a star, nor does it possess the characteristics to be considered a supermassive black hole (exclusive instead of the galactic centers, where density, temperature and gravity have infinitely higher values). The only possible explanation is therefore to make it fall into the category of intermediate class black holes: the missing piece for a broader understanding of the life cycle of black holes.
Michela Mapelli, professor at the Department of Physics and Astronomy of the University of Padua and associate INFN and INAF studied the astrophysical implications of Gw 190521 and stated: “This event is extraordinary: the mass of one of the two black holes that merged before our eyes is equal to about 85 times the mass of the Sun. Current models tell us that black holes with mass between 65 and 120 solar masses they cannot be formed from the collapse of a star. This new result will certainly lead to a paradigm shift in the field of black hole astrophysics“.
The co-author and co-reviewer of the study Alessandra Buonanno, director of Max Planck Institute for Gravitational Physics from Potsdam, Germany, wanted to add: “Despite the very short duration, we were able to associate the signal with the one expected for the merger of black holes, as predicted by Einstein’s theory of general relativity, and we realized that we have witnessed, for the first time, the birth of an intermediate-mass black hole from a parent black hole that most likely arose, in turn, from a previous binary merger.”
For now the authors have advanced several hypotheses, but the most probable one remains the one just mentioned chain fusion of intermediate black holes. We will certainly know more when the two interferometers complete a third series of observations. We will not fail to keep you updated.