The black hole-bulge relation in active galactic nuclei

We have used the widths of Hbeta and [O III] emission lines to investigate the black hole-bulge relation in radio-loud active galactic nuclei (AGNs), radio-quiet AGNs and narrow-line Seyfert 1 galaxies (NLS1s). The central black hole mass, M-bh, is estimated from the Hbeta linewidth and the optical luminosity, and the bulge velocity dispersion, sigma is directly estimated from the width of the [O III] line. We have found that radio-quiet AGNs follow the established M-bh-sigma relationship in nearby inactive galaxies, while radio-loud AGNs and NLS1s deviate from this relationship. There are two plausible interpretations for the deviation of radio-loud AGNs. One is that the size of broad-line regions (BLRs) emitting the Hbeta line is overestimated because of the overestimation of optical luminosity. The other is that the dynamics of BLRs and/or narrow-line regions in radio-loud AGNs is different from that in radio-quiet AGNs. The deviation of NLS1s may be due to the small inclination of BLRs to the line of sight or the reliability of the [O III] linewidth as the indicator of stellar velocity dispersion because of its complex multiple components.