The Search for Galaxy Clustering around a Quasar Pair at z =4.25 Found in the Sloan Digital Sky Survey

Abstract

We present an investigation of the environment (≈600 kpc radius) of a pair of luminous z = 4.25 quasars, SDSS J1439-0034A and B, separated by 33''. An analysis of high-quality Subaru spectra of the quasars suggests that this configuration is indeed a physical pair and not a gravitational lens; the redshifts are slightly different (although marginally consistent with being the same), and the two spectra have strikingly different features. We search for bright galaxies (L 0.4L*) having similar redshifts using the V dropout technique and semi-narrowband imaging looking for strong Lyα emission. We find no enhancement in the galaxy density around the quasar pair; its environment differs very little from a general field, with the upper limit of the density enhancement being about 3.5 at a 90% confidence. We infer that bright quasars happened to appear in two normal galaxies in a general field.