We present results from a 577 ks XMM- Newton observation of SPT-CL J0459 - 4947 , the most distant cluster detected in the South Pole Telescope 2500 square degree ( SPT-SZ ) survey , and currently the most distant cluster discovered through its Sunyaev-Zel ’ dovich effect .
The data confirm the cluster ’ s high redshift , z = 1.71 \pm 0.02 , in agreement with earlier , less precise optical/IR photometric estimates .
From the gas density profile , we estimate a characteristic mass of M _ { 500 } = ( 1.8 \pm 0.2 ) \times 10 ^ { 14 } M _ { \odot } ; cluster emission is detected above the background to a radius of \sim 2.2 r _ { 500 } , or approximately the virial radius .
The intracluster gas is characterized by an emission-weighted average temperature of 7.2 \pm 0.3 keV and metallicity with respect to Solar of Z / Z _ { \odot } = 0.37 \pm 0.08 .
For the first time at such high redshift , this deep data set provides a measurement of metallicity outside the cluster center ; at radii r > 0.3 r _ { 500 } , we find Z / Z _ { \odot } = 0.33 \pm 0.17 , in good agreement with precise measurements at similar radii in the most nearby clusters , supporting an early enrichment scenario in which the bulk of the cluster gas is enriched to a universal metallicity prior to cluster formation , with little to no evolution thereafter .
The leverage provided by the high redshift of this cluster tightens by a factor of 2 constraints on evolving metallicity models , when combined with previous measurements at lower redshifts .