Probing narrow-line Seyfert 1 galaxies in the southern hemisphere
  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.
