We report near-infrared K ’ , L ’ , and M ’ band imaging observations of the nearby merging galaxy NGC 6240 with the Infrared Camera and Spectrograph on the Subaru telescope .
The observations were performed with the assistance of the Subaru Adaptive Optics System , and the achieved spatial resolutions were around 0.10–0.20 ^ { \prime \prime } .
We also obtained new mid-infrared imaging in the Si-2 filter band ( 8.7 \mu m ) and N-band ( 7.5–13 \mu m ) spectroscopy of this galaxy with the CanariCam on the Gran Telescopio Canarias with a spatial resolution of 0.4–0.5 ^ { \prime \prime } .
In the K ’ band image the two nuclei of the galaxy each show a double-peak suggesting the complex geometry of the source , while the L ’ , M ’ , and Si-2 band images show single compact structures in each of the two nuclei .
Assuming that the center core observed at wavelengths longer than 3.8 \mu m is associated with dust heated by the buried AGN , we re-evaluated the spectral energy distributions ( SEDs ) of the southern nucleus from 2 to 30 \mu m with the additional literature values , and performed the SED+spectroscopy fitting using the clumpy torus models of Nenkova et al .
( 2008 ) and a Bayesian fitting approach .
The model fit suggests that the high covering factor torus emission in the southern nucleus is also obscured by foreground dust in the host galaxy .
The estimated AGN bolometric luminosity of the southern nucleus , L _ { bol } ( { AGN } ) \sim 1 \times 10 ^ { 45 } erg \cdot s ^ { -1 } , accounts for approximately 40 % of the whole luminosity of the system .