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B. Grossan (Instutue d'Astrophysque Spatiale, Orsay, France)
We present new Keck LWS Mid-IR (MIR) imaging observations of a sample of LLAGN. Our results show that nuclear 10 micron fluxes of NGC4203 and NGC4736, along with three other LLGN from previous work, correlate with X-ray flux with the same relation as more luminous Seyferts and quasars. The nuclear emission of our objects is clearly differentiated from that of starburst activity on a plot of MIR vs. X-ray flux. Because X-ray and MIR fluxes are nearly insensitive to dust extinction, this behavior suggests the same continuum origin for our LLAGN sample as for Seyferts.
MIR images of the nucleus of M81 show clearly extended, elliptical structure roughly 3.5" across the long axis (~70 pc at the source), confirming earlier, lower resolution measurements at Palomar. This structure, the relative MIR and X-ray nuclear fluxes, the lack of stellar emission sufficient to power the MIR flux, and a weak UV continuum, are evidence for material within the nucleus extinguishing an AGN which powers the MIR emission. A unified model torus may be the origin of the extinction.
The author gratefully acknowledges the support of the American Astronomical Society and the LBNL Institute for Nuclear and Particle Astrophysics (INPA) for this work.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.