Gemini imaging of mid-infrared emission from the nuclear region of centaurus a

We present high spatial resolution mid-IR images of the nuclear region of NGC 5128 (Centaurus A). Images were obtained at 8.8 μm, N band (10.4 μm), and 18.3 μm using the mid-IR imager/spectrometer T-ReCS on Gemini South. These images show a bright unresolved core surrounded by low-level extended emission. We place an upper limit to the size of the unresolved nucleus of 3.2 pc (0.19″) at 8.8 μm and 3.5 pc (0.21″) at 18.3 μm at the level of the FWHM. The most likely source of nuclear mid-IR emission is from a dusty torus and possibly a dusty narrow-line region with some contribution from synchrotron emission associated with the jet as well as relatively minor starburst activity. Clumpy tori models are presented which predict the mid-IR size of this torus to be no larger than 0.05″ (0.85 pc). Surrounding the nucleus is extensive low-level mid-IR emission. This paper presents to date the highest spatial resolution mid-IR images of this extended near nuclear structure, previously observed by ISO and Spitzer. Much of the emission is coincident with Paα sources seen by HST implying emission from star-forming areas; however, evidence for jet-induced star formation, synchrotron emission from the jet, a nuclear bar/ring, and an extended dusty narrow emission line region is also discussed. © 2008. The American Astronomical Society. All rights reserved.