Abstract:
We present a new catalog of narrow-line Seyfert 1 (NLSy1) galaxies from the Sloan Digital Sky Survey Data
Release 12 (SDSS DR12). This was obtained by a systematic analysis through modeling of the continuum and
emission lines of the spectra of all the 68,859 SDSS DR12 objects that are classified as “QSO” by the SDSS
spectroscopic pipeline with z < 0.8 and a median signal-to-noise ratio (S/N) > 2 pixel−1. This catalog contains a
total of 11,101 objects, which is about 5 times larger than the previously known NLSy1 galaxies. Their
monochromatic continuum luminosity at 5100 Å is found to be strongly correlated with Hβ, Hα, and [O III]
emission line luminosities. The optical Fe II strength in NLSy1 galaxies is about two times larger than the broadline Seyfert 1 (BLSy1) galaxies. About 5% of the catalog sources are detected in the FIRST survey. The Eddington ratio (xEdd) of NLSy1 galaxies has an average of log xEdd of −0.34, much higher than −1.03 found for BLSy1 galaxies. Their black hole masses (MBH) have an average of log MBH of 6.9 M, which is less than BLSy1 galaxies, which have an average of log MBH of 8.0 M. The MBH of NLSy1 galaxies is found to be correlated withm their host galaxy velocity dispersion. Our analysis suggests that geometrical effects playing an important role in defining NLSy1 galaxies and their MBH deficit is perhaps due to their lower inclination compared to BLSy1 galaxies.
