  Using archival as well as freshly acquired data, we assess the X-ray
behaviour of the Fermi/LAT gamma-ray pulsars listed in the First Fermi source
catalog. After revisiting the relationships between the pulsars' rotational
energy losses and their X and gamma-ray luminosities, we focus on the
distance-indipendent gamma to X-ray flux ratios. When plotting our Fgamma/Fx
values as a function of the pulsars' rotational energy losses, one immediately
sees that pulsars with similar energetics have Fgamma/Fx spanning 3 decades.
Such spread, most probably stemming from vastly different geometrical
configurations of the X and gamma-ray emitting regions, defies any
straightforward interpretation of the plot. Indeed, while energetic pulsars do
have low Fgamma/Fx values, little can be said for the bulk of the Fermi neutron
stars. Dividing our pulsar sample into radio-loud and radio-quiet subsamples,
we find that, on average, radio-quiet pulsars do have higher values of
Fgamma/Fx, implying an intrinsec faintness of their X-ray emission and/or a
different geometrical configuration. Moreover, despite the large spread
mentioned above, statistical tests show a lower scatter in the radio-quiet
dataset with respect to the radio-loud one, pointing to a somewhat more
constrained geometry for the radio-quiet objects with respect to the radio-loud
ones.
