Hawking radiation

Verification: This is a theoretical prediction of quantum field theory in curved spacetime. If a black hole emits Hawking radiation, it loses energy and the equivalent mass; for astrophysical black holes the expected rate is extraordinarily small, and evaporation times exceed the age of the universe by an immense margin. Hawking radiation from a real astrophysical black hole has not yet been directly detected.

Conclusion: Theory predicts that black holes slowly lose mass through Hawking radiation, but this has not been directly observed for ordinary astrophysical black holes.