Radio-loud high-redshift protogalaxy candidates in Bootes
  We used the Near Infrared Camera on Keck I to obtain Ks-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical to fainter than 24 Vega mag. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I / FR-II break. The other has photometric redshift 1.2, but may in fact be at higher redshift. Two of the four objects exhibit diffuse morphologies in Ks -band, suggesting that they are still in the process of forming. 
Steve Croft (1,2,3,4), Wil van Breugel (1,2), Michael J. I. Brown (5),   Wim de Vries (1,3), Arjun Dey (6), Peter Eisenhardt...