Near Infrared K- and L-band Spectroscopy of Low-Luminosity AGNs : Estimating the Contribution from Nuclear Starbursts

We report our first results of K- and L-band spectroscopic observations (SpeX on IRTF) for eight low-luminosity Seyfert galaxies to study the connection between nuclear starbursts and AGN activity. A polycyclic aromatic hydrocarbon (PAH) emission feature at 3.3 mu m in the L-band (2.8-4.1 mu m) is primarily used to investigate nuclear starburst activity in these galaxies. This result shows that the putative nuclear starbursts are occurred in the low-luminosity Seyfert galaxies. We find that there is no significant difference in nuclear starburst to AGN luminosity ratios of type 1 and 2 Seyfert galaxies. Whereas, we find that stellar luminosities in K-band estimated from the strength of the CO absorption features at 2.3-2.4 mu m produced by stellar photosphere of type 2 are statistically brighter than type 1. The result shows that it is possible that there is a bias AGN luminosity of type 2 is intrinsically brighter than type 1 in the samples selected by optical luminosity. If not, it is also possible the result plays an important role to understand the dust density distribution in the torus.