Abstract：Compact relativistic jets are commonly observed across multiple wavelengths during the hard-state outbursts of black hole X-ray binaries. If the axis of the jet is misaligned with the black hole spin, the jet will precess due to the effect of frame dragging of the spinning black hole. In this talk, I will present our first measurement of this jet-spin misalignment by modeling the phase-resolved spectra of X-ray quasi-periodic oscillations (QPOs) detected in MAXI J1820+070 during its hard state. Our result supports a geometric origin for QPOs within the black hole spacetime and provides direct observational evidence that the low-frequency QPOs (LFQPOs) in MAXI J1820+070 arise from jet precession.
Bio：Dr. Yefei Yuan is a Chair Professor at the University of Science and Technology of China (USTC). He earned his PhD from the USTC Center for Astrophysics in 1999 and has been a faculty member in the Department of Astronomy ever since. His research focuses on relativistic astrophysics—specifically compact objects such as neutron stars, black holes, and white dwarfs—and nuclear astrophysics, including the physics of dense nuclear matter and high-energy neutrinos.