Comment on the Black Hole Recoil Candidate Quasar SDSS J092712.65+294344.0

Understand

SDSS J092712.65+294344.0 has been proposed as a candidate for a supermassive black hole (~10^8.8 solar masses) ejected at high speed from the host galactic nucleus by gravitational radiation recoil, or alternatively for a supermassive black hole binary.

• This is based on a blueshift of 2650 km/s of the broad emission lines ("b-system") relative to the narrow emission lines ("r-system") presumed to reflect the galaxy velocity.
• New observations with the Hobby-Eberly Telescope (HET) confirm the essential features of the spectrum.
• We note a third redshift system, characterized by weak, narrow emission lines of [O III] and [O II] at an intermediate velocity 900 km/s redward of the broad line velocity ("i-system").