SIMBAD references

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.