Probing narrow-line Seyfert 1 galaxies in the southern hemisphere

TL;DR

This study presents a new catalog of 167 narrow-line Seyfert 1 galaxies in the southern hemisphere from the 6dFGS survey, analyzing their spectral properties, black hole masses, and radio characteristics.

Contribution

It provides the first flux-calibrated spectra for 6dFGS NLS1s and explores correlations between spectral lines, luminosities, and radio properties, expanding knowledge of southern NLS1s.

Findings

Strong correlation between 5100 A luminosity and Hbeta, [O III] lines

Average black hole mass of 8.6 million solar masses

Radio-loud NLS1s have higher redshift and luminosity

Abstract

We present a new accurate catalog of narrow-line Seyfert 1 galaxies (NLS1s) in the southern hemisphere from the Six-degree Field Galaxy Survey (6dFGS) final data release, which is currently the most extensive spectroscopic survey available in the southern sky whose database has not yet been systematically explored. We classified 167 sources as NLS1s based on their optical spectral properties. We derived flux-calibrated spectra for the first time that the 6dFGS indeed does not provide. By analyzing these spectra, we obtained strong correlations between the monochromatic luminosity at 5100 A and the luminosity of Hbeta and [O III]5007 lines. The estimated central black hole mass and Eddington ratio have an average value of 8.6 x 10^6 M_Sun and 0.96 L_Edd respectively, which is a typical value for NLS1s. In the sample, 23 (13.8%) NLS1s were detected at radio frequencies, and 12 (7.0%) of them are radio-loud. Our results confirmed that radio-loud sources tend to have a higher redshift, more massive black hole, and higher radio and optical luminosity than radio-quiet sources.