Frame dragging is a general relativistic effect in which a rotating mass drags spacetime around with it. Theoretical descriptions use the Lense-Thirring term in the Kerr metric and predict measurable consequences in the motion of matter and light near rotating black holes. Empirical support comes from multiple, independent observational techniques that converge on the same physical interpretation.
X-ray timing and spectral signatures
Broad, skewed iron K alpha emission lines and relativistic reflection spectra are interpreted as emission from the inner accretion disk that is distorted by strong gravity and rotation. Observational programs using XMM-Newton and NuSTAR have been analyzed by Andrew C. Fabian at University of Cambridge and Christopher S. Reynolds at University of Cambridge to infer rapidly rotating black hole spacetime geometries where frame dragging governs the disk inner edge and photon trajectories. Rapid variability known as quasi-periodic oscillations also provides evidence: timing campaigns with NASA's Rossi X-ray Timing Explorer reported low-frequency QPOs whose phase-resolved energy shifts are modeled as precession of the inner flow. Theoretical and observational modeling of such QPOs has been developed by Adam Ingram at the University of Amsterdam linking these oscillations to Lense-Thirring precession of tilted inner disks.
Imaging and jet observations
Direct imaging of the immediate environment of supermassive black holes gives complementary evidence. The Event Horizon Telescope produced asymmetric, crescent-shaped images of the black hole in M87 in work led by Sheperd Doeleman at the Harvard-Smithsonian Center for Astrophysics. Those images match general-relativistic ray-tracing models in which rotation and associated frame dragging shape the photon ring and Doppler-boosted emission. Large-scale relativistic jets whose direction and collimation appear coupled to black hole spin are consistent with mechanisms that rely on rotation, such as the Blandford-Znajek process; long-baseline radio monitoring shows jet alignment and sometimes precession that are plausibly tied to spin-induced torques.
Evidence is inherently model-dependent and indirect: spectral and timing signatures require relativistic ray-tracing and plasma physics to link observations to spacetime effects. Cross-validation among timing, spectroscopy, and very long baseline interferometry strengthens the overall case. International collaborations of observational facilities and theorists, and instruments distributed across multiple countries, play a decisive role in isolating frame dragging from environmental influences such as magnetic fields and disk turbulence, making the attribution to a rotating spacetime increasingly robust.