A New Near and Mid Infrared Diagnostic for Dust in AGN
Abstract
To study dust in Seyfert (Sy) galaxies, we have combined new high resolution N band photometry with 2MASS J and K band photometry to obtain color-magnitude and color-color relations for the central 1'' of 41 Active Galactic Nuclei (AGN) from the IRAS 12 micron sample. The J-K vs. absolute N band color-magnitude diagram shows a trend of increasing absolute N band luminosity with redder J-K colors. This result is consistent with a simple first-order picture in which an AGN with more emission at N, also has more emission at K, which dominates the K flux from the bulge stars and leads to a redder J-K color. The J-K vs K-N color-color diagram also shows an interesting relation. Most of the Sy's occupy a limited area of the color-color diagram, but there are many outliers which we believe represent two different dust distributions at work. Those galaxies with very red J-K colors seem to be those that have dust in their host galaxy reddening their nuclear light. On the other hand, those with very red K-N colors but with bulge-like J-K colors seem to have their intrinsic spectrum reddened by the dusty torus, totally obscuring the nuclear J and K flux, but re-radiating that flux at longer wavelengths.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AAS...199.4301G