We present the results from extensive , new observations of the Perseus Cluster of galaxies , obtained as a Suzaku Key Project .
The 85 pointings analyzed span eight azimuthal directions out to 2 ^ { \circ } = 2.6 \text { Mpc } , to and beyond the virial radius r _ { 200 } \sim 1.8 \text { Mpc } , offering the most detailed X-ray observation of the intracluster medium ( ICM ) at large radii in any cluster to date .
The azimuthally averaged density profile for r > 0.4 r _ { 200 } is relatively flat , with a best-fit power-law index \delta = 1.69 \pm 0.13 significantly smaller than expected from numerical simulations .
The entropy profile in the outskirts lies systematically below the power-law behavior expected from large-scale structure formation models which include only the heating associated with gravitational collapse .
The pressure profile beyond \sim 0.6 r _ { 200 } shows an excess with respect to the best-fit model describing the SZ measurements for a sample of clusters observed with Planck .
The inconsistency between the expected and measured density , entropy , and pressure profiles can be explained primarily by an overestimation of the density due to inhomogeneous gas distribution in the outskirts ; there is no evidence for a bias in the temperature measurements within the virial radius .
We find significant differences in thermodynamic properties of the ICM at large radii along the different arms .
Along the cluster minor axis , we find a flattening of the entropy profiles outside \sim 0.6 r _ { 200 } , while along the major axis , the entropy rises all the way to the outskirts .
Correspondingly , the inferred gas clumping factor is typically larger along the minor than along the major axis .