High-Resolution Near-Infrared Imaging of the Powerful Radio Galaxy 3C 324 at z = 1.21 with the Subaru Telescope

We have obtained high-resolution K ′ -band images of the powerful z = 1.206 radio galaxy 3C 324 with the Subaru telescope under seeing conditions of 0 ′′ .3–0 ′′ .4. We clearly resolved the galaxy and directly compared it to the optical images obtained with the Hubble Space Telescope. The host galaxy of 3C 324 is revealed to be a moderately luminous elliptical galaxy with a smooth light profile. The effective radius of the galaxy, as determined by profile fitting, is 1.3± 0 ′′ .1 (1.2 kpc), which is significantly smaller than the value of 2 ′′ .2 published in Best et al. (1998, MNRAS, 292, 758). The peak of the K ′ -band light coincides with the position of the radio core, which implies that the powerful AGN lies at the nucleus of the host galaxy. The peak also coincides with the gap in the optical knotty structures which may be a dust lane hiding the UV-optical emission of the AGN from our line of sight; it is very likely that we are seeing the obscuring structure almost edge-on. We clearly detected the ‘aligned component’ in the K ′ -band image by subtracting a model elliptical galaxy from the observed image. The red RF702W K color of the outer region of the galaxy avoiding the aligned component indicates that the near infrared light of the host galaxy is dominated by an old stellar population.