Measuring supermassive black holes with gas kinematics. II. The LINERs IC 989, NGC 5077, and NGC 6500

We present results from a kinematical study of the gas in the nucleus of a sample of three LINER galaxies, obtained from archival HST/STIS long-slit spectra. We found that, while for the elliptical galaxy NGC 5077, the observed velocity curves are consistent with gas in regular rotation around the galaxy's center, this is not the case for the two remaining objects. By modeling the surface brightness distribution and rotation curve from the emission lines in NGC 5077, we found that the observed kinematics of the circumnuclear gas can be accurately reproduced by adding to the stellar mass component a black hole mass of M_BH = 6.8_-2.8^+4.3× 10^8~M_⊙ (uncertainties at a 1σ level); the radius of its sphere of influence (R_sph ∼ 0.34 arcsec) is well-resolved at the HST resolution. The BH mass estimate in NGC 5077 is in fairly good agreement with both the M_BH-M_bul (with an upward scatter of ~0.4 dex) and M_BH-σ correlations (with an upward scatter of 0.5 dex in the Tremaine et al. form and essentially no scatter using the Ferrarese et al. form) and provides further support for the presence of a connection between the residuals from the M_BH-σ correlation and the bulge effective radius. This indicates the presence of a black hole's “fundamental plane” in the sense that a combination of at least σ and R_e drives the correlations between M_BH and host bulge properties.

Based on observations obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS 5-26555.