Did you know that in the Milky Way there are between 10 million and 1 billion black holes? Their particularity is to be invisible, except when they trap matter. Fortunately, they are still detectable by Science.
Moreover, an international team of scientists has detected an inactive and solitary black hole located nearly 5,200 light years away, according to Futura Sciences. In 2011, two science projects spotted a star that seemed to increase in brightness. Over the next six years, they observed this star and found that its brightness and position had changed, indicating here a phenomenon of gravitational microlensing.
How did they manage to detect it when it is invisible? Even though the black hole is not visible, it exerts gravity on its surroundings. The light, when it passes close to the black hole, is thus deflected. We can then note a change in the apparent position and brightness of the source of this light, depending on Futura Sciences. This phenomenon is scientifically called “gravitational microlensing”. These microlenses make it possible to detect various objects in the sky, such as faint stars, exoplanets or even wandering planets.
The researchers checked whether the object they were observing was a star or a black hole. But after several analyzes, they noted that the object did not emit any light of its own. They also calculated that the mass of the object was about seven times greater than that of the Sun. This therefore excluded the template of a star but corresponded perfectly to a standard black hole mass. “We show that the lens does not emit any detectable light, which, in addition to having a mass greater than what is possible for a white dwarf or a neutron star, confirms its nature as a black hole”, explains Kailash Sahu. , of the Space Telescope Science Institute, and colleagues.
The researchers’ paper, submitted to The Astrophysical Journal is awaiting validation by their peers.