Probing narrow-line Seyfert 1 galaxies in the southern hemisphere

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 does not provide. By analyzing these spectra, we obtained strong correlations between the monochromatic luminosity at 5100 Å and the luminosities of Hβ and [O III]λ5007 lines. The central black hole mass and the Eddington ratio have average values of 8.6 × 10<SUP>6</SUP>M<SUB>☉</SUB> and 0.96 L<SUB>Edd</SUB> respectively, which are typical values 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 higher redshift, a more massive black hole, and higher radio and optical luminosities than radio-quiet sources. <P />Tables 1, 2, 4, and 5 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/615/A167">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/615/A167</A>