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J.-H. Woo (Yale University)
Black hole mass (M\bullet) is a fundamental property of active galactic nuclei (AGNs). We collect and estimate M\bullet for a large sample of ~ 500 AGNs to investigate the relation of AGN activity to M\bullet. For a subsample of 39 AGNs at z<0.6, we measure and collect stellar velocity dispersion to investigate the evolution of host galaxies. We compare M\bullet estimates generated by different methods and find, for individual objects, a scatter as high as a couple of orders of magnitude. The less direct the method, the larger the discrepancy with other estimates, probably due to the large scatter in the underlying correlations assumed. In contrast to other studies, we find no significant correlation of M\bullet with AGN luminosity, other than those induced by circular reasoning in the estimation of M\bullet. M\bullet of radio-loud and radio-quiet AGNs span the same large range, 106-1010 M\odot, suggesting radio loudness in AGNs does not depend strongly on M\bullet. The M\bullet range for different BL Lac object spectral types is also similar, 107 \lesssim M\bullet/M\odot \lesssim 4 \times 109. Neither X-ray or radio luminosity correlates with M\bullet. Low-frequency-peaked BL Lac objects have higher Eddington ratios on average, because of either more beaming or larger intrinsic power. BL Lac object host galaxies and radio galaxies lie on the same fundamental plane as normal galaxies. Comparing the mass-to-light ratio evolution with our population synthesis models, we find that single burst star formation models with zform = 1.4+0.9 -0.2 are consistent with the observations. The estimated R band mass-to-light ratio evolution, \Delta log (M/L)/ \Delta z = -0.502, is consistent with that of normal early-type galaxies. The normality of AGN host galaxies supports the hypothesis that AGNs are a transient phase in the evolution of galaxies.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.