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G.A. Verdoes Kleijn (Leiden Observatory), S.A. Baum (STScI), P.T. de Zeeuw (Leiden Observatory), R.P. van der Marel, C.P. O'Dea, C. Xu (STScI), C.M. Carollo (Columbia University)
We observed the nuclei of a complete sample of 21 nearby (D < 70h-1 {\rm Mpc}) Fanaroff & Riley Type I galaxies using HST/WFPC2. The galaxies typically resemble normal ellipticals except for the presence of small (~1 '') central disks or lanes of dust and emission gas. Disks have outlines which closely resemble ellipses, while lanes are warped filaments. Disks are invariably well aligned with the stellar major axis while lanes are not. We describe possible scenarios to explain these differences. Half of the nuclei show unresolved nuclear blue emission. We argue this is synchrotron emission from the inner jet. We discuss the disk-jet relative orientations, the various correlations between radio and optical line and continuum fluxes, and describe the implications of these results for unifying schemes of FR I and BL Lac galaxies (see Baum et al.).
We are performing a follow-up study using HST/STIS observations (GO-8236) for 19 targets and archival data for two others. We obtain high resolution spectra from three parallel slits positioned along the stellar major axis to determine emission-line kinematics. The spectra cover the wavelength range from 6500Å-7000Å. For four targets we additionally obtain STIS low resolution spectra covering the wavelength range 2900Å-10270{Å} to determine emission-line ratios. So far ten targets have been observed. From the multiple slit spectra we infer to what extent the emission gas is in Keplerian rotation, and hence provide a measurement of the mass of the central black hole. The emission-line ratios constrain the ionization mechanism of the gas: photo- or shock-ionization.
The author(s) of this abstract have provided an email address for comments about the abstract: verdoes@strw.leidenuniv.nl