Measuring supermassive black holes with gas kinematics^*

II. The LINERs IC 989, NGC 5077, and NGC 6500

¹ INAF – Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Italy e-mail: [defrancesco;capetti]@oato.inaf.it
² Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, 50125 Firenze, Italy e-mail: marconi@arcetri.astro.it

Received: 29 August 2007
Accepted: 26 October 2007

Abstract

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 (uncertainties at a 1σ level); the radius of its sphere of influence () is well-resolved at the HST resolution. The BH mass estimate in NGC 5077 is in fairly good agreement with both the (with an upward scatter of ~0.4 dex) and 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 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.