2016ApJ...824..122K

We have performed a spectral decomposition to search for recoiling supermassive black holes (rSMBHs) in Sloan Digital Sky Survey (SDSS) quasi-stellar objects (QSOs) with z M_BH of the rSMBH candidates are on average ∼5 times smaller than those of their stationary counterparts and cause a scatter in the {M}_BH-σ_* relation. The Eddington ratios of all of the rSMBH candidates are larger than 0.1, with a mean of 0.52±0.27, suggesting that they are actively accreting mass. Velocity shifts in high-excitation coronal lines suggest that the rSMBH candidates are recoiling with an average velocity of about -265 km/s. The electron density in the narrow line region of the H ii rSMBH candidates is about 1/10 of that in active galactic nucleus (AGN) rSMBH candidates, probably because the AGN in the former was more spatially offset than that in the latter. The estimated spatial offsets between the rSMBH candidate and the center of the host galaxy range from 0.''21 to 1.''97 and need to be confirmed spatially with high-resolution adaptive optics imaging observations.