SDSS J1619 with blueshifted broad components in H α and in [O iii] having similar line width and velocity shifts: a recoiling SMBH candidate?

Abstract

ABSTRACT 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 MBHr derived from the broad H α is consistent with the mass expected from the MBH–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 MBH–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 MBH–σ relation cannot be explained by the other proposed models in SDSS J1619.