[O III] emission line in narrow-line Seyfert 1 galaxies

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 (NLS1s) 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 NLS1s are still deviated from the M-bh-sigma relation found in the nearby inactive galaxies. This suggests that the linewidth of the [O III] narrow/core component is likely not a good tracer of bulge velocity dispersion in NLS1s, since some other studies indicate that NLS1s, like other active galactic nuclei (AGN), should follow the M-bh-sigma relation. If we assume that the [O III]5007/H beta(n) line ratio emitted in the narrow-line region (NLR) ranges from one to 10, 63 objects are found to be 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 NLS1s, we find that one of these 63 objects (J143030.22-001115.1) cannot be classified as a genuine NLS1. Its narrow component of H beta is coming from NLRs. This is consistent with its very flat hard X-ray spectrum found by researchers.