| Title | Comparison of AGN and Nuclear Starburst Activity in Seyfert 1 and 2 Galaxies over a Wide Luminosity Range Based on Near-Infrared 2-4μm Spectroscopy |
| Authors | Oi, Nagisa; Imanishi, Masatoshi; Imase, Keisuke |
| Bibcode | 2010PASJ...62.1509O Search ADS ↗ |
| Abstract | We present near-infrared K- (1.9-2.5μm) and L- (2.8-4.2μm) band spectroscopy of 22 Seyfert nuclei. We used two methods to investigate the presence of nuclear starbursts: (1) the Polycyclic Aromatic Hydrocarbon (PAH) emission feature at λrest = 3.3μm in the rest frame of the K-band spectrum (a starburst indicator) and (2) the CO absorption feature at λrest = 2.3-2.4μm in the rest frame of the K-band spectrum, originating in the CO molecule. We clearly detected the 3.3μm PAH emission features in five objects and the CO absorption features in 17 objects. Seyfert 2 galaxies tend to show bluer K - L colors compared with Seyfert 1 galaxies. We interpret the discrepancy as resulting from the relative strength of stellar emission because AGN emission is affected by dust extinction. The 3.3μm PAH emission luminosity (L3.3PAH) distributions for the Seyfert 1s and Seyfert 2s are very similar when normalized to the AGN power. The star-formation rates estimated from L3.3PAH could be large enough to inflate the dusty torus by a supernova explosion. We find that L3.3PAH positively correlates with the N-band luminosity with small aperture over a wide AGN luminosity range, and is independent of the physical area we probed. The results suggest that the nuclear region has a concentration of star formation and it would control the AGN activity. |
| Objects | 40 Objects Search NED ↙ |
