A black hole, perturbed by a merger, vibrates at characteristic resonant frequencies — much like a bell ringing after being struck. Each hole has its own spectrum of these oscillations, allowing astronomers to reconstruct its parameters. In a recent theoretical study, scientists explored how this 'ringing' is influenced by two factors: dark energy, the mysterious substance responsible for the accelerated expansion of the universe, and hypothetical clouds of microscopic strings predicted by some theories of quantum gravity.

The objects of analysis were quantum black holes — extremely small objects where quantum effects can no longer be neglected. The researchers calculated how the presence of dark energy and string fields modifies the vibrational response of such holes. A key tool was the so-called 'greybody factor'—a quantity that quantifies how strongly the hole's gravitational potential impedes the escape of radiation. Without accounting for this factor, correctly decoding signals from gravitational waves, ripples in spacetime from cosmic cataclysms, would be impossible.

The results showed that both dark energy and the parameters of string configurations lead to a noticeable shift in the eigenfrequencies of oscillations and a change in the black hole's permeability to electromagnetic radiation. In other words, the hole's 'voice' is highly sensitive to subtle effects that go beyond classical general relativity.

These calculations are a conceptual step toward next-generation detectors. If such shifts can be isolated in observed signals, we could 'hear' not only the mass and angular momentum of the hole but also the contribution of dark energy in its vicinity. Remarkably, such mini-holes, presumably born in the first moments after the Big Bang, could carry echoes of that era to us.