Speaker
Description
Scalar ultralight boson clouds around rotating black holes can generate long-lived, non-axisymmetric gravitational perturbations capable of exciting coherent dynamical responses in nearby accretion flows. Focusing on black hole X-ray binaries, we investigate whether this forcing can excite global oscillations of a thin accretion disk and produce observable quasi-periodic variability. Using a linear-response framework for a simplified hydrodynamic disk model, we compare the characteristic frequency and spatial structure of the boson-cloud forcing with the intrinsic modes of the disk, while accounting for resonance structure and damping. We then connect the resulting disk perturbations to possible observational signatures through relativistic ray tracing. I will discuss the physical conditions under which the response may be amplified and the prospects for probing the resulting high-frequency variability with current or future X-ray timing observations.