Abstract:
We present a comparative study of the physical properties of a homogeneous sample of 144 Narrow line Seyfert 1 (NLSy1) and
117 Broad-line Seyfert 1 (BLSy1) galaxies. These two samples are in a similar luminosity and redshift range and have optical
spectra available in the 16th data release of Sloan Digital Sky Survey (SDSS-DR16) and X-ray spectra in either XMM-NEWTON
or ROSAT. Direct correlation analysis and a principal component analysis (PCA) have been performed using ten observational
and physical parameters obtained by fitting the optical spectra and the soft X-ray photon indices as another parameter. We
confirm that the established correlations for the general quasar population hold for both types of galaxies in this sample despite
significant differences in the physical properties. We characterize the sample also using the line shape parameters, namely the
asymmetry and kurtosis indices. We find that the fraction of NLSy1 galaxies showing outflow signatures, characterized by blue
asymmetries, is higher by a factor of about 3 compared to the corresponding fraction in BLSy1 galaxies. The presence of high
iron content in the broad-line region of NLSy1 galaxies in conjunction with higher Eddington ratios can be the possible reason
behind this phenomenon. We also explore the possibility of using asymmetry in the emission lines as a tracer of outflows in the
inner regions of Active Galactic Nuclei. The PCA results point to the NLSy1 and BLSy1 galaxies occupying different parameter
spaces, which challenges the notion that NLSy1 galaxies are a subclass of BLSy1 galaxies.
