On Strong Correlation between Shifted Velocity and Line Width of Broad Blueshifted [O iii] Components in Quasars

Abstract

Abstract We report strong linear correlation between shifted velocity and line width of the broad blueshifted [O iii] components in Sloan Digital Sky Survey (SDSS) quasars. Broad blueshifted [O iii] components are commonly treated as indicators of outflows related to a central engine; however, it is still an open question whether the outflows are related to central accretion properties or related to local physical properties of narrow emission-line regions (NLRs). Here, the reported strong linear correlation with Spearman rank correlation coefficient 0.75 can be expected under the assumption of active galactic nuclei (AGNs) feedback-driven outflows, through a large sample of 535 SDSS quasars with reliable blueshifted broad [O iii] components. Moreover, there are very different detection rates for broad blueshifted and broad redshifted [O iii] components in quasars, and no positive correlation can be found between shifted velocity and line width of the broad redshifted [O iii] components, which provides further and strong evidence to reject the possibility of local outflows in NLRs leading to the broad blueshifted [O iii] components in quasars. Thus, the strong linear correlation can be treated as strong evidence for the broad blueshifted [O iii] components being better indicators of outflows related to central engine in AGNs. Furthermore, rather than central black hole masses, Eddington ratios and continuum luminosities have key roles in the properties of the broad blueshifted [O iii] components in quasars.