We report on 3--4 micro m slit spectroscopy of 17 Seyfert 2 nuclei. The 3.3 micro m polycyclic aromatic hydrocarbon (PAH) emission was used to estimate the magnitude of compact (< a few hundred pc) nuclear starbursts. For three of the selected Seyfert 2 nuclei, the magnitudes of compact nuclear starbursts estimated from the 3.3 micro m PAH emission feature (with no extinction correction) were in satisfactory quantitative agreement with those based on UV observations after extinction correction, indicating that the observed 3.3 micro m PAH emission luminosity can be used to estimate the magnitude of compact nuclear starbursts in the nuclei of Seyfert 2s. We found that (1) except in one case, the observed nuclear 3--4 micro m fluxes were dominated by AGNs and not by starbursts, (2) compact nuclear starbursts were detected in 6 out of 17 Seyfert 2 nuclei, but cannot dominate the infrared dust emission luminosities in the majority of the observed Seyfert 2 galaxies, and (3) more powerful AGNs tended to be related to more powerful compact nuclear starbursts. In addition to those showing 3.3 micro m PAH emission, 3.4 micro m carbonaceous dust absorption was detected in two Seyfert 2 nuclei, and 3.05 micro m H2O ice absorption was detected in one nucleus, and possibly detected in one more.
The Proceedings of the IAU 8th Asian-Pacific Regional Meeting, Volume 1
- Pub Date:
- May 2003