A Study of Outflows in Luminous Quasars at Redshift $\sim0.4-0.8$
We perform a systematic study of outflow in the narrow-line region (NLR) of active galactic nuclei (AGNs) at $z\sim0.4-0.8$ basing upon a large sample of $\sim900$ quasars at $z\sim 0.4-0.8$. The sample is extracted from the Sloan Digital Sky Survey by mainly requiring 1) the g-band magnitude is brighter than 19 magnitude; and 2) the [OIII]$\lambda5007$ emission line has a signal-to-noise ration larger than 30. Profiles of multiple emission lines are modeled by a sum of several Gaussian functions. The spectral analysis allows us to identify 1) a prevalence of both [OIII]$\lambda5007$ line blue asymmetry and bulk velocity blueshift of both [NeIII]$\lambda3869$ and [NeV]$\lambda3426$ lines, when the [\ion{O}{2}]$\lambda3727$ line is used as a reference. The velocity offset of [\ion{O}{3}]$\lambda5007$ line is, however, distributed around zero value, except for a few outliers. 2) not only the significant [OIII]$\lambda5007$ line asymmetry, but also the large bulk velocity offsets of [NeIII]$\lambda3869$ and [NeV]$\lambda3426$ emission lines tend to occur in the objects with high $L/L_{\mathrm{Edd}}$, which is considerably consistent with the conclusions based on local AGNs. With three $M_{\mathrm{BH}}$ estimation methods, the significance level of the trend is found to be better than $2.9\sigma$, $3.2\sigma$ and $1.8\sigma$ for [OIII], [NeIII] and [NeV], respectively. \rm After excluding the role of radio jets, the revealed dependence of NLR gas outflow on $L/L_{\mathrm{Edd}}$ allows us to argue that the pressure caused by the wind/radiation launched/emitted from central supermassive black hole is the most likely origin of the outflow in these distant quasars, which implies that the outflow in luminous AGNs up to $z\sim1$ have the same origin.