The orbit of a star around a supermassive black hole gives reason to Einstein

A new study, published in "Science", confirms the validity of the theory of relativity. The investigation followed, for 26 years, the orbit of a star that allowed detailed calculation of gravity in extreme environments.

26,000 light-years from Earth, in the central regions of the Milky Way, it Find Sagittarius A *, a supermbadive black hole with a mbad equivalent to about four million suns. Black holes are objects so compact that even light can not escape their gravitational influence, and it is the detailed study of the orbits of nearby stars that has allowed them to know their mbad. (Read: History: they publish the first real image of a black hole)

Now, one of these stars, known as S2, allowed us to study in detail gravity in extreme environments and confirm the validity of Einstein's theory of relativity. The work, published in the magazine Science, had the participation of researchers from the Institute of Astrophysics of Andalusia CPISC.

Einstein, in his theory of relativity, showed that time and space, which had always been considered as separate entities, actually formed a single entity: space-time. (We suggest: scientific theories know more than their creators)

Space-time is the scenario in which all the physical events of the universe take place. It is a malleable tissue that bends in the presence of matter. This curvature is the cause of the gravitational effects that govern the movement of bodies (that of planets around the Sun and that of clusters of galaxies), and theThe supermbadive black holes are an ideal environment to verify this effect.

"Our observations are consistent with the theory of relativity – says Andrea Ghez, a researcher at the University of California, who is leading the work. However, relativity can not fully explain gravity in a black hole, and at some point we will have to go beyond Einstein to adopt a more complete theory of gravity that explains these extreme environments ", a- he stressed.

Gravitational Redshift

The results were possible thanks to the star S2, which draw a very pronounced ellipse around Sagittarius A * and that at the point of maximum approach, it is located only about three times the distance between the Sun and Pluto. At this distance, and because of the enormous gravity force of the black hole, relativity predicts that photons (light particles) should experience a loss of energy, called gravity redshift. This is precisely what the scientific team measured,confirming a result published in 2018.

"This type of experiments is subject to a lot of possible mistakes and, unfortunately, the team that released the previous result did not publish any data, which should be the norm today, says Rainer Schödel, a researcher at the Institute of Astrophysics of Andalusia. and one of the authors of the study. With this work, we provide an independent verification of an extremely difficult experience, very necessary in this case, and we provide all data and statistical badysis. "

Key data from the survey were taken with the Keck telescope (Hawaii) during the months of maximum approach between the star and the black hole. These data, in which Eulalia Gallego, a researcher at the same institute, was involved, were combined with measurements made over the last 24 years, resulting in the full orbit of the star in three dimensions and, in turn, check the validity. of general relativity. (Here: the sacred mountain in Hawaii)

"This result is a clear example of the galactic center's enormous potential as a laboratory, not only for studying galactic nuclei and their role in the evolution of galaxies, but also for solving fundamental physics problems. ", concludes Schödel, also a researcher. main project GALACTICNUCLEUS, which aims to solve outstanding problems by increasing by more than a hundred times our current knowledge of the closest stellar population of Sagittarius A *.