The Connection between 3.3 µm Polycyclic Aromatic Hydrocarbon Emission and Active Galactic Nucleus Activity

Abstract

We investigate the connection between starburst and active galactic nucleus (AGN) activity by comparing 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission with AGN properties. Utilizing the slitless spectroscopic capability of the AKARI space telescope, we observe a moderate-luminosity Type I AGN at z ~ 0.4 to measure global starburst activity. The 3.3 μm PAH emissions are detected for 7 out of 26 target galaxies. We find no strong correlation between the 3.3 μm PAH emission and AGN luminosity in the limited range of the observed AGN luminosity, suggesting that global star formation may not be closely related to AGN activity. Combining our measurements with previous 3.3 μm measurements of low-redshift Type I AGNs in the literature, we investigate the connection between nuclear starburst and AGN activity. In contrast to global star formation, the 3.3 μm PAH luminosity measured from the central part of galaxies correlates with AGN luminosity, implying that starburst activity and AGN activity are directly connected in the nuclear region.