  The acceleration and radiative processes active in low-power radio hotspots
are investigated by means of new deep near-infrared (NIR) and optical VLT
observations, complemented with archival, high-sensitivity VLT, radio VLA and
X-ray Chandra data. For the three studied radio galaxies (3C 105, 3C 195 and 3C
227), we confirm the detection of NIR/optical counterparts of the observed
radio hotspots. We resolve multiple components in 3C 227 West and in 3C 105
South and characterize the diffuse NIR/optical emission of the latter. We show
that the linear size of this component ($\gtrsim$4 kpc) makes 3C 105 South a
compelling case for particles' re-acceleration in the post-shock region.
Modeling of the radio-to-X-ray spectral energy distribution (SED) of 3C 195
South and 3C 227 W1 gives clues on the origin of the detected X-ray emission.
In the context of inverse Compton models, the peculiarly steep synchrotron
curve of 3C 195 South sets constraints on the shape of the radiating particles'
spectrum that are testable with better knowledge of the SED shape at low
($\lesssim$GHz) radio frequencies and in X-rays. The X-ray emission of 3C 227
W1 can be explained with an additional synchrotron component originating in
compact ($<$100 pc) regions, such those revealed by radio observations at 22
GHz, provided that efficient particle acceleration ($\gamma\gtrsim$10$^7$) is
ongoing. The emerging picture is that of systems in which different
acceleration and radiative processes coexist.

High Energy Astrophysical Phenomena