Examining the Radio-Loud/Radio-Quiet dichotomy with new Chandra and VLA observations of 13 UGC galaxies

(Abridged) We present the results from new 15 ks Chandra-ACIS and 4.9 GHz Very Large Array observations of 13 galaxies hosting low luminosity AGN. This completes the multiwavelength study of a sample of 51 nearby early-type galaxies described in Capetti & Balmaverde (2005, 2006); Balmaverde & Capetti (2006). The aim of the three previous papers was to explore the connection between the host galaxies and AGN activity in a radio-selected sample. We detect nuclear X-ray emission in eight sources and radio emission in all but one (viz., UGC6985). The new VLA observations improve the spatial resolution by a factor of ten: the presence of nuclear radio sources in 12 of the 13 galaxies confirms their AGN nature. As previously indicated, the behavior of the X-ray and radio emission in these sources depends strongly on the form of their optical surface brightness profiles derived from Hubble Space Telescope imaging, i.e., on their classification as core, power-law or intermediate galaxies. With more than twice the number of power-law and intermediate galaxies compared to previous work, we confirm with a much higher statistical significance that these galaxies lie well above the radio-X-ray correlation established in FRI radio galaxies and the low-luminosity core galaxies. This result highlights the fact that the radio-loud/radio-quiet dichotomy is a function of the host galaxys optical surface brightness profile. We present radio-optical-X-ray spectral indices for all 51 sample galaxies. Survival statistics point to significant differences in the radio-to-optical and radio-to-X-ray spectral indices between the core and power-law galaxies (Gehans Generalized Wilcoxon test probability p for the two classes being statistically similar is <10^-5), but not in the optical-to-X-ray spectral indices (p=0.25).

The rotating wind of the quasar PG 1700+518

It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that would otherwise inhibit accretion. Such winds are capable of depositing large amounts of mechanical energy in the host galaxy and its environs, profoundly affecting its formation and evolution, and perhaps regulating the formation of large-scale cosmological structures in the early Universe. Although there are good theoretical grounds for believing that outflows from active galactic nuclei originate as disk winds, observational verification has proven elusive. Here we show that structures observed in polarized light across the broad H-alpha emission line in the quasar PG 1700+158 originate close to the accretion disk in an electron scattering wind. The wind has large rotational motions (~4,000 km/s), providing direct observational evidence that outflows from active galactic nuclei are launched from the disks. Moreover, the wind rises nearly vertically from the disk, favouring launch mechanisms that impart an initial acceleration perpendicular to the disk plane.