2017MNRAS.468..620Z

In this manuscript, we check the well-known correlation between [O III] luminosity and continuum luminosity (L_ [O  III]_–L 5100 ^○_ A_ ) for active galactic nuclei (AGN) by a large sample of 1982 Sloan Digital Sky Survey Quasar Stellar Objects (QSOs) with z < 0.8 and with high-quality spectra. The strong correlation of L_ [O  III]_–L 5100 ^○_ A_ can be found, similar as previous results for AGN. Moreover, among the 1982 QSOs, there are 708 QSOs with the [O III] λ5007 Å described by two components: one core component plus one extended component. Based on the luminosity from the core components (L_ [O  III], narrow_) and from the extended components (L_ [O  III], ext_), we confirm that the correlation of L_ [O  III], ext_–L 5100 ^○_ A_ is stronger and tighter than the correlations on the total [O III] luminosity and on the luminosity of the core components of the [O III] lines. Therefore, the luminosity of the extended components should be better applied to trace AGN intrinsic luminosity. Meanwhile, we have found strong line-width correlation and line luminosity correlation between the core components and the extended components, indicating that the extended components of the [O III] lines should be not due to commonly considered radial flows in the common [O III] line clouds. And virial effects due to gravity of central black holes naturally lead to the wider extended components from regions more nearer to central black holes. Finally, we can say that the reported correlation of L_ [O  III], narrow_–L 5100 ^○_ A_ on the core components of the [O III] lines should be more better to estimate AGN intrinsic luminosity in type-2 narrow-line AGN, because of totally/partly obscured extended components.