Obscured binary quasar cores in SDSS J104807.74+005543.5?

We report the discovery of a possible close binary system of quasars in SDSS J1048 + 0055. The [ O III] lambdalambda4959, 5007 emission lines are clearly double-peaked, and two discrete radio sources with a projected physical separation of similar to 20 pc are found in the Very Long Baseline Array milliarcsecond resolution image at 8.4 GHz. Each of the [ O III] lambdalambda4959, 5007 doublets and Hbeta can be well modeled by two Gaussians, and the line ratio [O III] lambda5007/Hbeta similar to 7 is typical of Seyfert 2 galaxies. No broad component of Hbeta was detected, and its [O III] lambda5007 luminosity, L-[O III] approximate to 9.2 x 10(42) ergs s(-1), is comparable to luminous quasars and is a few x 10 more luminous than typical Seyfert galaxies. One natural interpretation is that SDSS J1048 + 0055 contains two close quasarlike nuclei, and the broad-line region around them is obscured. Other possible models are also discussed. We suggest that a double-peaked narrow emission line profile may be an effective way of selecting candidates of binary black holes with intermediate separation.