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??m, N band (10.4??m), and 18.3??m 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??m and 3.5 pc (0.21 -->'') at 18.3??m 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 Pa? 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.

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