X-ray Spectroscopy of the Virgo Cluster out to the Virial Radius
  We present results from the analysis of a mosaic of thirteen XMM-Newton
pointings covering the Virgo Cluster from its center northwards out to a radius
r~1.2 Mpc (~4.5 degrees), reaching the virial radius and beyond. This is the
first time that the properties of a modestly sized (M_vir~1.4e14 M_sun, kT~2.3
keV), dynamically young cluster have been studied out to the virial radius. The
density profile of the cluster can be described by a surprisingly shallow
power-law with index 1.21+/-0.12. In the radial range of 0.3r_vir<r<r_vir, the
best fit temperature drops by roughly 60 per cent. Within a radius r<450 kpc,
the entropy profile has an approximate power-law form with index 1.1, as
expected for gravitationally collapsed gas in hydrostatic equilibrium. Beyond
r~450 kpc, however, the temperature and metallicity drop abruptly, and the
entropy profile becomes flatter, staying consistently below the expected value
by a factor of 2-2.5. The most likely explanation for the unusually shallow
density profile and the flattening of entropy at large radius is clumping in
the ICM. Our data provide direct observational evidence that the ICM is
enriched by metals all the way to r_200 to at least Z=0.1 Solar.
