THE EFFECTS OF X-RAY ILLUMINATION ON ACCRETION DISK INTERIORS

We investigate the structure of accretion disks illuminated by X-rays from a central compact object. At radii larger than a certain value, X-ray heating can dominate the viscous heating and determine the disk structure in a standard alpha-disk model. We calculate the disk structure resulting from X-ray illumination both analytically and numerically for low-mass X-ray binaries as well as for active galactic nuclei. We show that X-ray illumination does have important effects on the disk structures under a variety of circumstances and that instabilities may arise under significant X-ray heating.