TALK ABSTRACT:
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We present X-ray observations of the nuclear region of 25 Fanaroff-Riley 
Type I (FRI) radio galaxies from the 3CRR and B2 catalogs, using data from the
Chandra and XMM archives.  We find the presence of a X-ray Central Compact
Core (CCCX) in 13/25 sources, in 3/25 sources the detection of a CCCX
is uncertain, while in the remaining 9/25 sources no CCCX is found.  All
the sources are embedded in a diffuse soft X-ray component, generally
on kpc-scales, which is in agreement with the halo of the host galaxy
and/or with the intracluster medium.  The X-ray spectra of the cores
are described by a power law with photon indices Gamma = 1.1 - 2.6.  In
8 sources excess absorption over the Galactic value is detected, with
rest-frame column densities N_H^z ~ 10^20 - 10^21 cm^-2; thus, we confirm
the previous claim based on optical data that most FRI radio galaxies
lack a standard optically-thick torus.  We find significant correlations
between the X-ray core luminosity and the radio and optical luminosities,
suggesting that at least a fraction of the X-ray emission originates
in a jet; however, the origin of the X-rays remains ambiguous.  If the
X-ray emission is entirely attributed to an isotropic, accretion-related
component, we find very small Eddington ratios, L_bol/L_Edd ~ 10^-3 - 10^-8,
and we calculate the radiative efficiency to be eta ~ 10^-2 - 10^-6, 
based on the Bondi accretion rates from the spatial analysis.  This
suggests that radiatively inefficient accretion flows are present in
the cores of low-power radio galaxies.