Infrared Imaging of z=2.43 Radio Galaxy B3 0731+438 with the Subaru Telescope - Detection of H$\alpha$ Ionization Cones of a Powerful Radio Galaxy

We report on infrared imaging observations of the z = 2.429 radio galaxy B3 0731+438 with the Subaru telescope. The images were taken with the K′-band filter and the 2.25 μm narrow-band filter to examine the structure and properties of the Hα+[NII] λλ 6548, 6583 emission-line components. The Hα+[NII] emission-line image shows biconical lobes with an extent of 40 kpc, which are aligned with the rad...