A direct image of the obscuring disk surrounding an active galactic nucleus

Active galactic nuclei (AGN) are generally accepted to be powered by the release of gravitational energy in a compact accretion disk surrounding a massive black hole1,2; such disks are also thought necessary to collimate the powerful radio jets seen in some AGN3. The unifying classification schemes for AGN further propose that differences in their appearance can be attributed to the opacity of the accreting material, 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 gas4, although evidence for such disks has been mostly indirect, as their angular size is much smaller than the resolution of conventional telescopes. Here we report direct images of a parsec-scale disk of ionized gas within the nucleus of NGC1068, the archetype of obscured AGN. The disk is viewed nearly edge-on, and individual clouds observed within the ionized disk are opaque to high-energy radiation, consistent with the unifying classification schemes. The projected 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 accretion disk.