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

## TL;DR

This paper introduces a comprehensive catalog of over 11,000 narrow-line Seyfert 1 galaxies from SDSS DR12, revealing their distinct properties and correlations with black hole mass and host galaxy features.

## Contribution

It provides the largest and most systematically analyzed catalog of NLSy1 galaxies, with detailed spectral modeling and new insights into their physical characteristics.

## Key findings

- NLSy1 galaxies are about five times more numerous than previously known.
- They have higher Fe II strength and Eddington ratios compared to BLSy1 galaxies.
- Black hole masses in NLSy1 are lower and correlated with host galaxy velocity dispersion.

## 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 per pixel. 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 A is found to be strongly correlated with H-beta, H-alpha, and [O III] emission line luminosities. The optical Fe II strength in NLSy1 galaxies is about two times larger than the broad- line 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 Msun, which is less than BLSy1 galaxies, which have an average of log MBH of 8.0 Msun. The MBH of NLSy1 galaxies is found to be correlated with 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.