[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]$λλ$4959, 5007 and H$β$ 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]$λ$5007 to trace the stellar velocity dispersion instead of using the total linewidth of [O III]$λ$5007, we found that the SDSS NLSls are still deviated from the $M_{bh}-σ$ 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 $M_{bh}-σ$ relation. If we assume that the [O III]5007/H$β_{n}$ line ratio emitted in narrow line region ranges from one to ten, 63 objects are found to satisfied with this criterion and their H$β$ broad components should be used to calculate their virial black hole masses. These 63 objects are statically consistent with the $M_{bh}-σ_{[O III]}$ 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$β$ is coming from narrow line regions (NLRs). This is consistent with its very flat hard X-ray spectrum found by williams et al. (2004).