High Resolution Mid-IR Images of the Nucleus of M81

Abstract

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 1970's 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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References in corpus (4)

• The Spectral Energy Distributions of Low-Luminosity Active Galactic Nuclei
• Possible Evidence for Truncated Thin Disks in the Low-Luminosity Active Galactic Nuclei M81 and NGC 4579
• Discovery of Radio Outbursts in the Active Nucleus of M81
• Variability of Quasars at 10 microns

Cited by in corpus (8)

• Nuclear Activity in Nearby Galaxies
• The subarcsecond mid-infrared view of local active galactic nuclei: I. The N- and Q-band imaging atlas
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• IRAC Observations of M81
• Detection of the "Active" Nucleus of M32
• Anomalous Silicate Dust Emission in the Type 1 LINER Nucleus of M81
• Dust and PAH emission in the star-forming active nucleus of NGC 1097
• H-alpha +[NII] Observations of the HII Regions in M81