The outflow impacts on the size of the narrow-line region among type-2 AGNs

We present the study of the gas kinematics in narrow-line regions (NLRs) of 2,009 type-2 AGNs at $z<0.34$. We construct the [O III]$\lambda$5007 emission-line images using publicly available broadband images from the Sloan Digital Sky Survey (SDSS). The [O III] emission area of the samples, measured down to $1.4\times {10}^{-15}$ erg/s/cm${}^2$/arcsec${}^2$, ranges from 3.7 kpc${}^2$ up to 224 kpc${}^2$. With our broadband technique, we found the strong correlation between [O III] area and AGN luminosity inferred from the [O III] luminosity and the mid-infrared luminosity at the rest-frame $15\mu$m. The isophotal threshold used to determine the [O III] area affects the correlation strength in that the brighter isophote yields the stronger correlation between the [O III] area and AGN luminosity. The presence of gas outflow is examined by the ratio of the [O III] velocity dispersion to the stellar velocity dispersion (${\sigma }_{[\mathrm{O}\mathrm{I}\mathrm{I}\mathrm{I}]}\mathrm{/}{\sigma }_{\star }>1.4$) using the SDSS spectra. At the given luminosity, the objects with and without outflows exhibit the same extension of the [O III] emission. Their correlation between the [O III] area and luminosity is almost identical. It is suggested that the size of NLRs is not affected by outflow mechanisms but rather by photoionization from the central AGNS.