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Register a new userHigh Resolution Mid-IR Images of the Nucleus of M81
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B. Grossan
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We observed two nearby galaxies with potential or weak indications of nuclear activity, M32 and M81, with the MIRLIN mid-IR camera at N band (10.79 microns). M32 is not detected, but we give detailed measurements of the nucleus of M81. Our observations of M81 show a bright nuclear point source at N, and comparison to measurements made in the early 1970s gives an increase in nuclear flux of nearly a factor of two. If the comparison is accurate, the nuclear mid-IR emission must ultimately be powered by a variable, compact source, similar to that in Seyferts and quasars. M81 has been classified in the literature as a low-luminosity LINER, not a pure Seyfert galaxy. Further, it has been suggested that this and other low-luminosity AGN may have intrinsically different spectra than Seyferts and quasars. However, we find that the relative fluxes in the X-ray, MIR, and radio bands, all essentially unaffected by extinction and galaxy pollution, show a nuclear continuum remarkably like that of a bona fide Seyfert or quasar.
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We present diffraction limited, 10um imaging polarimetry data for the central regions of the archetypal Seyfert AGN, NGC1068. The position angle of polarization is consistent with three dominant polarizing mechanisms. We identify three distinct regions of polarization: (a) north of the nucleus, arising from aligned dust in the NLR, (b) south, east and west of the nucleus, consistent with dust being channeled toward the central engine and (c) a central minimum of polarization consistent with a compact (<22pc) torus. These observations provide continuity between the geometrically and optically thick torus and the host galaxys nuclear environments. These images represent the first published mid-IR polarimetry from an 8-m class telescope and illustrate the potential of such observations.
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