Physical origin of low-frequency quasi-periodic oscillations

Determine the physical origin of low-frequency quasi-periodic oscillations in black-hole X-ray binaries, including the mechanisms responsible for their observed timing and energy-dependent properties.

Background

Low-frequency quasi-periodic oscillations are commonly observed in black-hole X-ray binaries and are thought to probe processes occurring near the black hole. The paper notes that, despite extensive observational and theoretical work, no consensus has been reached regarding their physical origin. Proposed explanations include geometric mechanisms such as Lense–Thirring precession, transition-layer oscillations, shock oscillations, and variability of the Comptonizing region.