An international team of scientists has proven that rotating black holes can have “hair”, that is, additional parameters that depend on the absorbed matter. An article by researchers revealing the nature of anomalous structures was published in the journal Physical Review Letters.
Physicists usually characterize black holes with three parameters: mass, charge and rotation speed. However, for many years, scientists have been looking for features in black holes that would indicate the existence of unknown fundamental fields. In a new study, the results of numerical simulations showed that a scalar field arises in black holes as they spin fast enough.
Einstein’s theory of gravity and many of its extensions indicate that black holes cannot have stable “hairs” due to the radiation of gravitational waves. This is known as the no-hair theorem, which means that you cannot get additional information about matter that has fallen beyond the event horizon. It is impossible to distinguish a black hole formed by antimatter from a black hole made of ordinary matter. At the same time, there is no rigorous mathematical proof of the theorem. It has been shown that under some conditions “hair” can still appear.
Scalar field is used in some theories of gravity to describe the gravitational field.