An international research team relied on data from the European Space Agency’s (ESA) Gaia Observatory to study the behavior of a sun-like star with strange orbital characteristics. Due to the nature of its orbit, the team concluded that it must be part of a binary black hole system. In this way, it becomes the closest black hole to our Solar System and implies the existence of a considerable population of inactive black holes in our galaxy.
In a new study recently published on arXiv, researchers from around the world have announced the discovery of the closest black hole to the Solar System, orbiting a star similar to the Sun in terms of age and mass, at a distance of approximately 1,500 light-years from Earth. Land. It is an inactive black hole, which only accompanies the star but is not “devouring” it as in traditional binary systems.
The research was led by Kareem El-Badry, an astrophysicist at the Harvard-Smithsonian Center and the Max Planck Institute for Astronomy. He worked alongside a large number of scientists from the most important specialized centers on the planet, such as the Center for Computational Astrophysics of the Flatiron Institute in New York, the California Institute of Technology (Caltech), the Weizmann Institute of Science or the Paris Observatory , among other institutes and universities. The paper describing his findings is forthcoming in the Monthly Notices of the Royal Astronomical Society.
hidden in the shadows
The discovery was made possible after analyzing 168,065 stars that make up ESA’s Gaia Observatory catalogue, which appeared to have two-body orbits. According to an article published in Universe Today, they found a particularly promising candidate, a yellow G-type star, dubbed Gaia BH1. Based on the observed orbital behavior, El-Badry and his colleagues determined that this star must have a black hole companion, even though it did not behave like a conventional binary system. It is not even ruled out that planets may be discovered in this system dominated by Gaia BH1.
Using a method similar to that used to identify exoplanets, Doppler spectroscopy, the scientists observed and measured the gravitational forces that influence the orbit of the star and its companion. These follow-up observations confirmed that Gaia BH1 was orbiting alongside a companion of approximately 10 solar masses. It would be the first black hole in the Milky Way that was not discovered based on its X-ray emissions: traditional binary systems are detected by X-rays when the black hole swallows the accompanying star, but in this case it is of an inactive black hole.
hidden and lurking
Current models predict that the Milky Way contains about 100 million black holes, although we have only observed about 20 of them so far. However, all previously discovered black holes are active, binary X-ray systems: the black hole is eating a companion star and glows brightly in X-rays as that material’s energy is converted to light.
According to the researchers, these brighter black holes only represent the tip of the iceberg: A much larger population may be hiding in binaries separated by greater distances, in which the black hole only orbits the star but does not feed on it. The discovery of Gaia BH1 sheds light on this population of dormant black holes: scientists believe that dozens of similar systems could be identified in future studies.