VORTICES ON ACCRETION DISKS

EVERY rotating cosmic fluid that can be observed sufficiently closely displays either vortices or magnetic flux tubes on its surface; examples are tornadoes in the Earth's atmosphere 1, the Great Red Spot and other vortices in Jupiter's atmosphere, and sunspots. We suggest here that hot accretion disks also produce coherent objects, and that these vortices and magnetic flux tubes will cause significant dissipation and other observable physical effects. They will facilitate the escape of collimated radiation from deep within hot disks, producing spectral changes and time variability in the radiation from the disk. In the case of active galactic nuclei, modification of X-ray spectra due to the presence of vortices on accretion disks permits us to explain several observational puzzles, including short-term variability and the low degree of linear polarization.