Super massive black holes in disk galaxies: HST/STIS observations for 3 new objects

We present long-slit HST/STIS measurements of the ionized-gas kinematics in the nucleus of three disk galaxies, namely NGC 2179, NGC 4343, NGC 4435. The sample galaxies have been selected on the basis of their ground-based spectroscopy, for displaying a strong central velocity gradient for the ionized gas, which is consistent with the presence of a circumnuclear Keplerian disk (CNKD, Bertola et al. 1998; Funes et al. 2002) rotating around a super massive black hole (SMBH). For each target galaxy we obtained the Hα and [NII] 6583 A kinematics along the major axis and two 0.25-arcsec parallel offset positions. Out of three objects only NGC 4435 turned out to have a disk of ionized gas in regular motion and a regular dust-lane morphology. Preliminary modeling indicates a SMBH mass (M_BH) one order of magnitude lower than the one expected from the M_BH-sigma relation for galaxies (Ferrarese & Merritt 2000; Gebhardt et al. 2000).