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 galaxy's 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
(Gehan's 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).
