Stationary scalar and vector clouds around Kerr-Newman black holes

Understand

Massive bosons in the vicinity of Kerr-Newman black holes can form pure bound states when their phase angular velocity fulills the synchronisation condition, i.e.

• at the threshold of superradiance.
• The presence of these stationary clouds at the linear level is intimately linked to the existence of Kerr black holes with synchronised hair at the non-linear level.
• These configurations are very similar to the atomic orbitals of the electron in a hydrogen atom.