2024MNRAS.527L.167Z

In this letter, we report a potential candidate of recoiling supermassive black hole (rSMBH) in Sloan Digital Sky Survey (SDSS) J1619 based on similar velocity shifts and line widths of the blueshifted broad components in H α and [O III] doublet. The measured line width ratio between blueshifted broad H α and broad [O III] line is 1.06, if compared with common values around 5.12 for normal Type-1 active galactic nuclei, indicating different properties of the blueshifted broad components in SDSS J1619 from those of normal Quasi Stellar Objects (QSOs). The virial BH mass M_BHr derived from the broad H α is consistent with the mass expected from the M_BH-σ relation. The similar velocity shifts and line widths of the blueshifted broad components in H α and [O III] and the virial BH mass derived from the H α broad line emissions that is consistent with the mass expected from the M_BH-σ relation, can be explained by an rSMBH scenario. Besides the rSMBH scenario, either the similar line widths of the blueshifted broad components in H α and in [O III] or the consistency between the virial BH mass and the mass expected from the M_BH-σ relation cannot be explained by the other proposed models in SDSS J1619.