Deep Submillimeter Imaging of Dust Structures in Centaurus A

Images covering the central 450×100 (∼ 8.0×2.0 kpc) of NGC5128 (Centaurus A) obtained using SCUBA at 850 and 450μm with beam sizes of 14.5 and 8 respectively, are presented. These data are compared with those obtained at other wavelengths, in particular the optical, mid-infrared, and far-infrared continuum. The sensitive 850 and 450μm images show that the submillimeter (submm) continuum morphology and spectral index distribution of Centaurus A comprise four regions: an unresolved AGN core, an inner jet interacting with gas in the dust lane, an inner disk of radii ∼ 90, and colder outer dust. The inner disk has a high surface brightness, reverse-S-shaped feature in the 850 and 450μm images that coincides with the regions of intense 7 and 15μm continuum and a region of active star-formation. The infrared (IR) and submm images appear to reveal the same material as predicted by a geometric warped disk model consisting of tilted rings. We suggest this scenario is more plausible than that recently proposed in literature suggesting that the mid-IR emission in Centaurus A is primarily from a bar, with a structure that is different from the extended warped disk alone. A dust mass total of 2.2 × 10M⊙ has been calculated within a radius of 225 , 45% of which is in the star-forming region of radius ∼ 90 about the nucleus. Subject headings: dust — galaxies: active — galaxies: individual (Centaurus A, NGC5128) — galaxies: structure — submillimeter — radiation mechanisms: thermal