O III] Emission Line in Narrow-line Seyfert 1 Galaxies

Abstract

Three sets of two-component profiles are used to simultaneously model the [O III]$\lambda\lambda$4959, 5007 and H$\beta$ lines for the Fe II-subtracted spectra of 149 narrow line Seyfert 1 galaxies (NLSls) from the Sloan Digital Sky Survey (SDSS). Using the linewidth of the narrow/core component of [O III]$\lambda$5007 to trace the stellar velocity dispersion instead of using the total linewidth of [O III]$\lambda$5007, we found that the SDSS NLSls are still deviated from the $M_{bh}-\sigma$ relation found in the nearby inactive galaxies, suggesting that the linewidth of the [O III] narrow/core component is likely not a good tracer of bulge velocity dispersion in NLSls, since some other studies indicate that NLS1s, like other AGN, should follow the $M_{bh}-\sigma$ relation. If we assume that the [O III]5007/H$\beta_{n}$ line ratio emitted in narrow line region ranges from one to ten, 63 objects are found to satisfied with this criterion and their H$\beta$ broad components should be used to calculate their virial black hole masses. These 63 objects are statically consistent with the $M_{bh}-\sigma_{[O III]}$ relation. With the Chandra observation of some SDSS NLSls, for one object in these 63 objects, J143030.22-001115.1, we found that it can't be classified as a genuine NLS1. Its narrow component of H$\beta$ is coming from narrow line regions (NLRs). This is consistent with its very flat hard X-ray spectrum found by williams et al. (2004).