Gas clumping in the outskirts of the Virgo cluster
  Observations of the ICM in the outskirts of the Virgo cluster with Suzaku
have found the gas mass fraction in the northern direction to be significantly
above the expected level, indicating that there may be a very high level of gas
clumping on small scales in this direction. Here, we explore the XMM-Newton
data in the outskirts of Virgo, dividing it into a Voronoi tessellation to
separate the bulk ICM component from the clumped ICM component. As the nearest
galaxy cluster, Virgo's large angular extent allows the spatial scale of the
tessellation to be much smaller than has been achieved using the same technique
on intermediate redshift clusters, allowing us to probe gas clumping on the
scales down to 5$\times$5 kpc. We find that the level of gas clumping in the
outskirts to the north is relatively mild, ($\sqrt{C} < 1.1$), suggesting that
our point-source detection procedure may have excluded a significant fraction
of clumps. While correcting for clumping brings the gas mass fraction at
$r_{200}$ into agreement with the universal gas mass fraction, the values
outside $r_{200}$ remain significantly above it. This may suggest that
non-thermal pressure support in the outskirts to the north is significant, and
we find that a non-thermal pressure support at the level of 20 per cent of the
total pressure outside $r_{200}$ can explain the high gas mass fraction to the
north, which is in agreement with the range expected from simulations.
