On the BH-galaxy relation of AGN and Narrow Line Seyfert 1 Galaxies

Massive black holes (BHs) are detected in the centers of many nearby galaxies are linearly correlated with the luminosity of the host bulge (spheroid), the black hole mass being about 0.1% of the stellar mass. In active galaxies, the BH mass is best measured by the reverberation mapping (light echo) technique. We and others have shown that in AGNs the BH mass follows the same relation with the luminosity of the host galaxy as in ordinary (inactive) galaxies, with the exception of narrow line AGNs which apparently have significantly lower values of the BH/bulge mass (or BH/bulge luminosity) ratio. The BH/bulge ratio is also found to be strongly correlated with the velocity dispersion of the broad line-emitting gas in the active nucleus. However, in the BH-stellar velocity relation the difference between broad- and narrow-line AGNs (in particular NLS1s) seems to be less obvious. We review the subject adding recent updates and suggestions.