New corroborative evidence for the overdensity of galaxies around the radio-loud quasar SDSS J0836+0054 at z=5.8

Recently, Zheng et al. (2006) found evidence for an overdensity of galaxies around a radio-loud quasar, SDSS J0836+0054, at z = 5.8 (a 5 arcmin(2) field). We examined our deep optical imaging data (B, V, r', i', z', and NB816) taken with the Suprime-Cam on the Subaru Telescope. The NB816 narrow-band filter (X, 815 nm and Delta lambda = 12 nm) is suitable to search for Ly alpha emitters at z approximate to 5.7. We found a new strong Ly alpha emitter at z approximate to 5.7 close to object 13, identified by Zheng et al. (2006). Further, the non-detection of nine objects selected by Zheng et al. (2006) in our B, V, and r' images provides corroborative evidence to indicate that they are high-z objects.