Asymmetric emission of the [OIII]$\lambda$5007 profile in narrow-line Seyfert 1 galaxies

Abstract

Many active galactic nuclei (AGN) and particularly narrow-line Seyfert 1 (NLS1) galaxies, usually exhibit blueshifts and blue wings in several emission lines, which are mainly associated with outflows and strong winds. In order to study the radial velocity difference between the narrow component of H$\beta$ and the core component of [OIII]$\lambda$5007 and the asymmetric emission of this forbidden line, we investigate a sample of NLS1 galaxies . One of the aims of this paper is to analyze the blue wings of the [OIII]$\lambda$5007 profiles and their relation with the central engine. We have obtained and studied medium-resolution spectra (190 km s$^{-1}$ FWHM at H$\beta$) of a sample of 28 NLS1 galaxies in the optical range 4300 - 5200\AA. We performed Gaussian decomposition to the H$\beta$ and [OIII]$\lambda\lambda$4959,5007 emission profiles in order to study the distinct components of these lines. A new blue outlier galaxy is found, in which the center of the core component of [OIII] is blueshifted by 405 km s$^{-1}$ relative to the center of the narrow component of H$\beta$ line. We confirmed a previously known correlation between the blueshift and the full width half maximum (FWHM) of the core component of [OIII]$\lambda$5007 line. We also corroborated the correlation between the latter and the velocity of the centroid of the blue wing. On the other hand, by studying the radial velocity difference between the blue end of the asymmetric emission and the centroid of the core component of [OIII], we found a correlation between it and the central black hole mass and, therefore, with the luminosity of the broad component of H$\beta$. Finally, we found a moderate correlation between the luminosity of the [OIII] blue wing and the black hole mass.