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Paper: Low-luminosity Active Galaxies and their Central Black Holes
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 442
Authors: De Robertis, M.M.; Dong, X.Y.
Abstract: Central black hole masses for 117 spiral galaxies representing morphological stages S0/a through Sc and taken from the large spectroscopic survey of Ho et al. (1997) are derived using 2MASS Ks data. Black hole (BH) masses are found using a calibrated black-hole mass–Ks bulge luminosity relation, while bulge luminosities are measured using a two-dimensional bulge/disk decomposition routine.

The BH masses are correlated against a variety of nuclear and host-galaxy properties. Nuclear properties such as line width and line ratios show a very high degree of correlation with BH mass. The excellent correlation with line width supports the view that the emission-line gas is in virial equilibrium with either the BH or bulge potential. The very good emission-line ratio correlations may indicate a change in ionizing continuum shape with BH mass in the sense that more massive BHs generate harder spectra.

Apart from the inclination-corrected rotational velocity, no excellent correlations are found between BH mass and host-galaxy properties.

Significant differences are found between the distributions of BH masses in early (S0/a, Sa), middle (Sab-Sbc) and later (Sc) type spiral galaxies in the sense that early-type galaxies have preferentially larger central BHs. The line-width distributions show a marked difference among the sub-samples in the sense that earlier-type galaxies have larger line widths. There are also clear differences in line ratios between sub-samples likely related to the level of ionization in the gas.

Finally, a Ks-band Simien & de Vaucouleurs diagram shows excellent agreement with the original B-band relation.

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