Scientists have discovered the first wandering black hole in history that travels through our galaxy. Using the Hubble Space Telescope, the team not only detected an exile object, but also directly measured its mass – something that researchers in the past could only guess. The black hole is located approximately 5,000 light years from Earth in the spiral arm of the Sagittarius Kiel of the Milky Way. The mass of the celestial nomad is seven times the mass of the Sun. The black hole is moving at a speed of about 162,200 km/h.
When a huge star, about 20 times of the Sun mass, runs out of nuclear fuel, it collapses. This process creates either a neutron star or a black hole, and all this is accompanied by a supernova explosion. If the supernova is not perfectly symmetrical, it can give the star remnant a “push” that will throw it in a spiral. The black hole most likely received this “birth shock” at the time of the supernova explosion.
Because black holes do not emit light, astronomers use a method called astrometric or gravitational microlensing to detect them.
To date, terrestrial telescopes have recorded 30,000 microlensing events, and scientists have used these events to study all kinds of objects, such as stars, brown dwarfs and even exoplanets. However, microlensing events caused by black holes last longer than events caused by other objects.
If scientists were right in their conclusions, then this method can help confirm the number of similar objects in our galaxy, which have long been predicted by astronomers and cosmologists.
“We looked at five candidate black holes, but only one of them is possibly a black hole,” scientists said. “This tells us that our Milky Way galaxy has about 100 million black holes in it (opens in new tab). As we find more black holes, we can pin down the total number of black holes and their other properties more precisely.”
The new discovery not only relies on general relativity to confirm the existence of this single black hole, but also confirms Einstein’s general theory of relativity or geometric gravity from 1915, and the concept of mass formation and space-time distortion.