Narrow-line Seyfert 1 galaxies ( NLS1s ) are arguably one of the key AGN subclasses in investigating the origin of the black hole mass - stellar velocity dispersion ( M _ { BH } - \sigma _ { * } ) relation because of their high accretion rate and significantly low M _ { BH } .
Currently , it is under discussion whether present-day NLS1s offset from the M _ { BH } - \sigma _ { * } relation .
Using the directly measured stellar velocity dispersion of 93 NLS1s at z < 0.1 , and M _ { BH } estimates based on the updated mass estimators , we investigate the M _ { BH } - \sigma _ { * } relation of NLS1s in comparison with broad-line AGNs .
We find no strong evidence that the NLS1s deviates from the M _ { BH } - \sigma _ { * } relation , which is defined by reverberation-mapped type 1 AGNs and quiescent galaxies .
However , there is a clear trend of the offset with the host galaxy morphology , i.e. , more inclined galaxies toward the line-of-sight have higher stellar velocity dispersion , suggesting that the rotational broadening plays a role in measuring stellar velocity dispersion based on the single-aperture spectra from the Sloan Digital Sky Survey .
In addition , we provide the virial factor \log f = 0.05 \pm 0.12 ( f = 1.12 ) , for M _ { BH } estimators based on the FWHM of H \beta , by jointly fitting the M _ { BH } - \sigma _ { * } relation using quiescent galaxies and reverberation-mapped AGNs .