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We present a new catalog of narrow-line Seyfert 1 (NLSy1) galaxies from theSloan Digital Sky Survey Data Release 12 (SDSS DR12). This was obtained by asystematic analysis through modeling of the continuum and emission lines of thespectra of all the 68,859 SDSS DR12 objects that are classified as "QSO" by theSDSS spectroscopic pipeline with z < 0.8 and a median signal-to-noise ratio(S/N) > 2 per pixel. This catalog contains a total of 11,101 objects, which isabout 5 times larger than the previously known NLSy1 galaxies. Theirmonochromatic continuum luminosity at 5100 A is found to be strongly correlatedwith H-beta, H-alpha, and [O III] emission line luminosities. The optical Fe IIstrength in NLSy1 galaxies is about two times larger than the broad- lineSeyfert 1 (BLSy1) galaxies. About 5% of the catalog sources are detected in theFIRST survey. The Eddington ratio (XEdd) of NLSy1 galaxies has an average oflog XEdd of -0.34, much higher than -1.03 found for BLSy1 galaxies. Their blackhole masses (MBH) have an average of log MBH of 6.9 Msun, which is less thanBLSy1 galaxies, which have an average of log MBH of 8.0 Msun. The MBH of NLSy1galaxies is found to be correlated with their host galaxy velocity dispersion.Our analysis suggests that geometrical effects playing an important role indefining NLSy1 galaxies and their MBH deficit is perhaps due to their lowerinclination compared to BLSy1 galaxies.

A Catalog of Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Data Release 12