A DIRECT IMAGE OF THE OBSCURING DISK SURROUNDING AN ACTIVE GALACTIC NUCLEUS

Active galactic nuclei (AGN) are generally accepted to be powered by t he release of gravitational energy in a compact accretion disk surroun ding a massive black hole(1,2); such disks are also thought necessary to collimate the powerful radio jets seen in some AGN(3). The unifying classification schemes for AGN further propose that differences in th eir appearance can be attributed to the opacity of the accreting mater ial, which may obstruct our view of the central region of some systems . The popular model for the obscuring medium is a parsec-scale disk of dense molecular gas(4), although evidence for such disks has been mos tly indirect, as their angular size is much smaller than the resolutio n of conventional telescopes. Here we report direct images of a parsec -scale disk of ionized gas within the nucleus of NGC1068, the archetyp e of obscured AGN. The disk is viewed nearly edge-on, and individual c louds observed within the ionized disk are opaque to high-energy radia tion, consistent with the unifying classification schemes. The project ed axes of the disk and AGN are aligned, from which we infer that the ionized gas disk traces the outer regions of the long-sought inner acc retion disk.