Astronomers believe they have finally discovered the first “wandering” invisible black hole of its kind, wandering the vast expanse of our galaxy all alone. The discovery of this black hole was only possible when this invisible space object passed between the Earth and a bright star on the far side, refracting the light from this star by its extremely powerful gravity.
Note that for quite some time astronomers have observed a large discrepancy between the number of known black holes and their same number according to the predictions of modern cosmological models. But this discrepancy does not cause much surprise to anyone, because black holes are objects, detection of which is quite difficult. Many black holes mark their presence with bright disks of surrounding hot matter, bursts of radiation of various types and gravitational waves generated by their collisions. But, apparently, in the depths of space there are even more black holes that produce no effects at all and remain completely invisible to outside observers.
However, such invisible black holes still leave one single loophole for their detection, which is the gravitational lens effect known to our readers. Since a black hole almost always moves in the presence of some background radiation or light, its gravity will refract that light, making it appear as if a small, completely transparent lens is moving across the sky. And for several years, astronomers have been searching for such moving gravitational lenses, whose presence cannot be explained in terms of visible cosmic objects such as stars and galaxies.
Back in 2011, two independent projects – Microlensing Observations in Astrophysics (MOA) in New Zealand and Optical Gravitational Lensing Experiment (OGLE) in Chile – were launched in parallel. Over the past few years, scientists from these projects have examined data collected by the Hubble Space Telescope and other astronomical instruments to find stars that have undergone brightness changes for no apparent reason. With such data, scientists located such stars and were finally able to track the movement of a single gravitational lens across the night sky.
The scientists then performed a check that the gravitational lens was created by a black hole and not by some old star in the final stage of its life cycle. Analysis of the data showed that the object does not emit any light of its own, and its mass exceeds the mass of the Sun by a factor of seven. This mass is just in the range of masses of small black holes, and it is too large for an object of this mass to be a neutron star or a white dwarf.
Also, the scientists were able to determine that the invisible black hole moves at a speed of 45 kilometers per second and is at a distance of 5 thousand light years from us. It is likely that in its single journey this black hole went, having received a “kick” from the explosion of a supernova, together with which it was once part of one star system.
Astronomical scientists claim that this case is the first unequivocal discovery of a wandering black hole in the history of astronomy. And, thanks to the data and experience obtained during the study, the discovery of other such “wanderers” will not be long in coming, especially given the emergence of new astronomical tools with ample opportunities for this.
