THE ORIGIN OF WARPED, PRECESSING ACCRETION DISKS IN X-RAY BINARIES

The radiation-driven warping instability discovered by Pringle holds c onsiderable promise as the mechanism responsible for producing warped, precessing accretion disks in X-ray binaries. This instability is an inherently global mode of the disk, thereby avoiding the difficulties with earlier models for the precession. Here we follow up on earlier w ork to study the linear behavior of the instability in the specific co ntext of a binary system. We treat the influence of the companion as a n orbit-averaged quadrupole torque on the disk. The presence of this e xternal torque allows the existence of solutions in which the directio n of precession of the warp is retrograde with respect to disk rotatio n, in addition to the prograde solutions that exist in the absence of external torques.