Shaving Off Soft Hairs and Black Hole Image Memory Effect

The study explores the images of soft-haired Kerr black holes, revealing that these images experience rotation, dilation, and drifting compared to bald black holes. These effects are time-independent but direction-dependent, with drifting occurring at a constant speed. The soft hair of black holes can change due to gravitational or electromagnetic wave emissions, leading to the image memory effect, which serves as evidence for soft hair. The magnitude of this effect is proportional to the mass and spin of the large black hole but decreases with the mass ratio of a smaller accompanying black hole. However, detecting this effect is challenging due to the limited angular resolution of current and future detectors, especially if cosmological expansion is not considered.