They discover a black hole that “floats” through the galaxy
Astronomers believe that the death of large stars is the origin of black holes, so there would be hundreds of millions of them scattered throughout the Milky Way. The problem is that these isolated black holes are invisible.
Now, a team from the University of California have discovered what a floating black hole may be for the first time by observing the glow of a more distant star as its light is distorted by the object’s strong gravitational field.
Astronomers estimate that the mass of the invisible object is between 1.6 and 4.4 times that of the Sun. Since the remnant of a dead star must weigh more than 2.2 the mass of the Sun, the researchers suspect that it could be a neutron star instead of a black hole, some dense and very compact objects, but with gravity balanced by the internal pressure of the neutrals, which prevents a collapse.
“This is the first free-floating black hole or neutron star discovered with gravitational microlensing,” explained Jessica Lu, professor of astronomy at the University. ‘With this technology we can probe these solitary compact objects and weigh them. It’s a window into these dark objects,” she added.
Determining how many of these compact objects populate the galaxy will help astronomers understand the evolution of stars, particularly how they die, and perhaps reveal whether any of the unseen black holes are primordial black holes, which some experts believe were produced in large amounts during the Big Bang.