  Entropy is an advantageous diagnostics to study the thermodynamic history of
the intracluster plasma of galaxy clusters. We present the entropy profile of
the Abell 2244 galaxy cluster derived both exclusively using X-ray data from
the low-background Swift XRT telescope and also using Planck y data. The
entropy profile derivation using X-rays only is robust at least to the virial
radius because the cluster brightness is large compared to the X-ray background
at low energies, temperature is strongly bounded by the lack of cluster X-ray
photons at energies kT>3 keV, and the XRT background is low, stable and
understood. In the observed solid angle, about one quadrant, the entropy radial
profile deviates from a power-law at the virial radius, mainly because of a
sharp drop of the cluster temperature. This bending of the entropy profile is
confirmed when X-ray spectral information is replaced by the Compton map.
Clumping and non-thermal pressure support are insufficient to restore a power
law entropy profile because they are bound to be small by: a) the agreement
between mass estimates from different tracers (gas and galaxies), b) the
agreement between entropy profile determinations based on combinations of
observables with different sensitivities and systematics, and c) the low value
of clumping as estimated using the azimuthal scatter and the gas fraction.
Based on numerical simulations, ion-electron equilibration is also insufficient
to restore a linear entropy profile. Therefore, the bending of the entropy
profiles seems to be robustly derived and witnesses the teoretically-predicted
decrease in the inflow through the virial boundary.
