SDSS J1619 with blue-shifted broad components in Hα and in [O iii] having similar line width and velocity shifts: a recoiling SMBH candidate?

Abstract In this Letter, we report a potential candidate of recoiling supermassive black hole (rSMBH) in SDSS J1619 based on similar velocity shifts and line widths of the blue-shifted broad components in Hα and [O iii] doublet. The measured line width ratio between blue-shifted broad Hα and broad [O iii] line is 0.93, if compared with common values around 5.12 for normal Type-1 AGN, indicating different properties of the blue-shifted broad components in SDSS J1619 from those of normal QSOs. The virial BH mass MBHr derived from the broad Hα is consistent with the mass expected from the MBH − σ relation. The similar velocity shifts and line widths of the blue-shifted broad components in Hα and [O iii] and the virial BH mass derived from the Hα broad line emissions that is consistent with the mass expected from the MBH − σ relation, can be explained by a rSMBH scenario. Besides the rSMBH scenario, either the similar line widths of the blue-shifted broad components in Hα and in [O iii] or the consistency between the virial BH mass and the mass expected from the MBH − σ relation cannot be explained by the other proposed models in SDSS J1619.