Silicate absorption in heavily obscured galaxy nuclei

Abstract

Spectroscopy at 8-13 microns with T-ReCS on Gemini-S is presented for 3 galaxies with substantial silicate absorption features, NGC 3094, NGC 7172 and NGC 5506. In the galaxies with the deepest absorption bands, the silicate profile towards the nuclei is well represented by the emissivity function derived from the circumstellar emission from the red supergiant, mu Cephei which is also representative of the mid-infrared absorption in the diffuse interstellar medium in the Galaxy. There is spectral structure near 11.2 microns in NGC 3094 which may be due to a component of crystalline silicates. In NGC 5506, the depth of the silicate absorption increases from north to south across the nucleus, suggestive of a dusty structure on scales of 10s of parsecs. We discuss the profile of the silicate absorption band towards galaxy nuclei and the relationship between the 9.7 micron silicate and 3.4 micron hydrocarbon absorption bands.

7 pages, accepted for publication in MNRAS

Cited by in corpus (5)

• The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models
• The Origin of the Silicate Emission Features in the Seyfert 2 Galaxy, NGC 2110
• 9.7 micrometer Silicate Absorption in a Damped Lyman-alpha Absorber at z=0.52
• On the Anomalous Silicate Emission Features of AGNs: A Possible Interpretation Based on Porous Dust
• The unusual UV continuum of quasar Ton 34 and the possibility of crystalline dust absorption