EDP Sciences
Free access
Volume 380, Number 1, December II 2001
Page(s) 31 - 39
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20011429

A&A 380, 31-39 (2001)
DOI: 10.1051/0004-6361:20011429

On black hole masses, radio-loudness and bulge luminosities of Seyfert galaxies

Xue-Bing Wu1, 2 and J. L. Han2, 3

1  Department of Astronomy, Peking University, Beijing 100871, PR China
2  National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
3  The partner group of Max-Planck-Institut für Radioastronomie at National Astronomical Observatories of China
    e-mail: hjl@bao.ac.cn

(Received 8 June 2001 / Accepted 19 September 2001 )

We estimated black hole masses for 9 Seyfert 1 and 13 Seyfert 2 galaxies in the Palomar and CfA bright Seyfert samples using the tight correlation between black hole mass and bulge velocity dispersion. Combining other 13 Seyfert 1s and 2 Seyfert 2s in these samples but with black hole masses measured recently by reverberation mapping and stellar/gas dynamics, we studied the correlations of black hole masses with radio-loudness and bulge luminosities for a sample of 37 Seyfert galaxies. We found that if radio-loudness is measured using the optical and radio luminosities of the nuclear components, the black hole masses of radio-loud Seyfert 1s tend to increase with the radio-loudness. The black hole masses of all Seyfert galaxies increase with the radio power, but Seyfert galaxies have larger radio powers than nearby galaxies with the same black hole masses. In addition, the correlation between black hole masses and bulge V-band luminosities for Seyfert galaxies is consistent with that found for quasars and normal galaxies. The combined sample of 37 Seyfert galaxies, 15 quasars and 30 normal galaxies suggests a possible universal nonlinear relation between black hole and bulge masses, ${M_{\rm BH} \propto M}_{\rm bulge}^{1.74 \pm 0.14}$, which is slightly steeper than that found recently by Laor (2001) for a smaller sample. This nonlinear relation is supported by a larger sample including 65 Seyfert galaxies. The different ${M_{\rm BH}/ M}_{\rm bulge}$ ratio for galaxies with different bulge luminosities or different black hole masses may be explained by this relation. These results are consistent with some theoretical implications and are important for understanding the nature of radio emissions and the formation and evolution of supermassive black holes and galaxies.

Key words: black hole physics -- galaxies: active -- galaxies: nuclei -- galaxies: Seyfert

Offprint request: Xue-Bing Wu, wuxb@bac.pku.edu.cn

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