We present an analysis of high-quality X-ray data out to the virial radius for the two galaxy clusters Abell 1246 and GMBCG J255.34805+64.23661 ( J255 ) by means of our entropy-based SuperModel .
For Abell 1246 we find that the spherically-averaged entropy profile of the intracluster medium ( ICM ) progressively flattens outwards , and that a nonthermal pressure component amounting to \approx 20 \% of the total is required to support hydrostatic equilibrium in the outskirts ; there we also estimate a modest value C \approx 1.6 of the ICM clumping factor .
These findings agree with previous analyses on other cool-core , relaxed clusters , and lend further support to the picture by Lapi et al .
( 2010 ) that relates the entropy flattening , the development of nonthermal pressure component , and the azimuthal variation of ICM properties to weakening boundary shocks .
In this scenario clusters are born in a high-entropy state throughout , and are expected to develop on similar timescales a low entropy state both at the center due to cooling , and in the outskirts due to weakening shocks .
However , the analysis of J255 testifies how such a typical evolutionary course can be interrupted or even reversed by merging especially at intermediate redshift , as predicted by Cavaliere et al .
( 2011b ) .
In fact , a merger has rejuvenated the ICM of this cluster at z \approx 0.45 by reestablishing a high entropy state in the outskirts , while leaving intact or erasing only partially the low-entropy , cool core at the center .