Witnessing the Growth of the Nearest Galaxy Cluster: Thermodynamics of
  the Virgo Cluster Outskirts
  We present results from Suzaku Key Project observations of the Virgo Cluster,
the nearest galaxy cluster to us, mapping its X-ray properties along four long
`arms' extending beyond the virial radius. The entropy profiles along all four
azimuths increase with radius, then level out beyond $0.5r_{200}$, while the
average pressure at large radii exceeds Planck Sunyaev-Zel'dovich measurements.
These results can be explained by enhanced gas density fluctuations (clumping)
in the cluster's outskirts. Using a standard Navarro, Frenk and White (1997)
model, we estimate a virial mass, radius, and concentration parameter of
$M_{200}=1.05\pm0.02\times10^{14}$ M$_\odot$, $r_{200}=974.1\pm5.7$ kpc, and $c
= 8.8 \pm0.2$, respectively. The inferred cumulative baryon fraction exceeds
the cosmic mean at $r\sim r_{200}$ along the major axis, suggesting enhanced
gas clumping possibly sourced by a candidate large-scale structure filament
along the north-south direction. The Suzaku data reveal a large-scale sloshing
pattern, with two new cold fronts detected at radii of 233 kpc and 280 kpc
along the western and southern arms, respectively. Two high-temperature regions
are also identified 1 Mpc towards the south and 605 kpc towards the west of
M87, likely representing shocks associated with the ongoing cluster growth.
Although systematic uncertainties in measuring the metallicity for low
temperature plasma remain, the data at large radii appear consistent with a
uniform metal distribution on scales of $\sim 90\times180$ kpc and larger,
providing additional support for the early chemical enrichment scenario driven
by galactic winds at redshifts of 2-3.
