In this Letter we explore the hypothesis that the quasar SDSSJ092712.65+294344.0 is hosting a massive black hole binary embedded in a circumbinary disc .
The lightest , secondary black hole is active , and gas orbiting around it is responsible for the blue–shifted broad emission lines with velocity off-set of 2650 km s ^ { -1 } , relative to the galaxy rest frame .
As the tidal interaction of the binary with the outer disc is expected to excavate a gap , the blue-shifted narrow emission lines are consistent with being emitted from the low-density inhomogeneous gas of the hollow region .
From the observations we infer a binary mass ratio q \approx 0.3 , a mass for the primary of M _ { 1 } \approx 2 \times 10 ^ { 9 } M _ { \odot } , and a semi-major axis of 0.34 pc , corresponding to an orbital period of 370 years .
We use the results of cosmological merger trees to estimate the likely-hood of observing SDSSJ092712.65+294344.0 as recoiling black hole or as a binary .
We find that the binary hypothesis is preferred being one hundred times more probable than the ejection hypothesis .
If SDSSJ092712.65+294344.0 hosts a binary , it would be the one closest massive black hole binary system ever discovered .