  Relativistic Lense-Thirring precession of a tilted inner accretion disk
around a compact object has been proposed as a mechanism for low-frequency
(~0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray
binaries. A substantial misalignment angle (~15-20 degrees) between the
inner-disk rotation axis and the compact-object spin axis is required for the
effects of this precession to produce observable modulations in the X-ray light
curve. A consequence of this misalignment is that in high-inclination X-ray
binaries the precessing inner disk will quasi-periodically intercept our line
of sight to the compact object. In the case of neutron-star systems this should
have a significant observational effect, since a large fraction of the
accretion energy is released on or near the neutron-star surface. In this
Letter I suggest that this specific effect of Lense-Thirring precession may
already have been observed as ~1 Hz QPOs in several dipping/eclipsing
neutron-star X-ray binaries.
