Gaia GraL: Gaia DR2 Gravitational Lens Systems. VII. XMM-Newton
  Observations of Lensed Quasars
  We present XMM-Newton X-ray observations of nine confirmed lensed quasars at
$1 \lesssim z \lesssim 3$ identified by the Gaia Gravitational Lens program.
Eight systems are strongly detected, with 0.3--8.0 keV fluxes $F_{0.3-8.0}
\gtrsim 5 \times 10^{-14}\ {\rm erg}\ {\rm cm}^{-2}\ {\rm s}^{-1}$. Modeling
the X-ray spectra with an absorbed power law, we derive power law photon
indices and 2--10 keV luminosities for the eight detected quasars. In addition
to presenting sample properties for larger quasar population studies and for
use in planning for future caustic crossing events, we also identify three
quasars of interest: a quasar that shows evidence of flux variability from
previous ROSAT observations, the most closely-separated individual lensed
sources resolved by XMM-Newton, and one of the X-ray brightest quasars known at
$z>3$. These sources represent the tip of discovery that will be enabled by
SRG/eROSITA.
