Abstract
We have used the widths of Hβ 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 I galaxies (NLS1s). The central black hole mass, M bh , is estimated from the Hβ linewidth and the optical luminosity, and the bulge velocity dispersion, a, is directly estimated from the width of the [O III] line. We have found that radio-quiet AGNs follow the established M bh -σ 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 HAS 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.
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