The black holes at the galaxy’s core
Scientists have finally confirmed the existence of a dozen black holes at the heart of the Milky Way—and they believe there may be many thousands more. Lying at the center of our galaxy is a supermassive black hole, Sagittarius A*, that is about 4 million times the mass of the sun. Astronomers have long suspected that Sagittarius A* is surrounded by black holes. But because these enigmatic celestial bodies are invisible—their gravitational field is so strong that even light can’t escape—they’re extremely hard to find. In this case, scientists studied old observations gathered by NASA’s Chandra X-ray telescope to look for “binary” systems: black holes with an orbiting star, which together emit telltale radiation. They identified 12 black holes in total, all within a few light-years of Sagittarius A*. Because binary systems account for only a small proportion of black holes overall, they calculated that 10,000 other black holes must be lurking in the same area. With an abundance of dust and gas, the galaxy’s center is a “hothouse” for black hole formation, reports BBC.com. “[It’s] sort of like a little farm,” says lead author Chuck Hailey, an astrophysicist at Columbia University, “where you have all the right conditions to produce and hold on to a large number of black holes.” The dust and gas first form large stars, which collapse inward when they die and become black holes.