An XMM-Newton spatially-resolved study of metal abundance evolution in   distant galaxy clusters
  We present an XMM-Newton analysis of the X-ray spectra of 39 clusters of galaxies at 0.4<z<1.4, covering a temperature range of 1.5<=kT<=11 keV. We performed a spatially resolved spectral analysis to study how the abundance evolves with redshift not only through a single emission measure performed on the whole cluster but also spatially resolving the cluster emission. We do not observe a statistically significant (>2sigma) abundance evolution with redshift. The most significant deviation from no evolution (90% c.l.) is observed in the emission from the whole cluster (r<0.6r500), that could be parametrized as Z=A*(1+z)^(-0.8+/-0.5). Dividing the emission in 3 radial bins, no significant evidence of abundance evolution could be observed fitting the data with a power-law. A substantial agreement with measures presented in previous works is found. The error-weighted mean of the spatially resolved abundances in 3 redshift bins is consistent to be constant with z. Although the large error bars in the measure of the weighted-mean abundance prevent us from claiming any significant spatially resolved evolution, the trend with z in the 0.15-0.4r500 radial bin complements nicely the measures of Maughan et al., and broadly agrees with theoretical predictions. We also found that the data points derived from the spatially resolved analysis are well fitted by the relation Z(r,z)=Z0*(1+(r/0.15r500)^2)^(-a)*((1+z)/1.6)^(-gamma), showing a significant negative trend of Z with the radius and no significant evolution with the redshift. The present study is the first attempt made to spatially resolve the evolution of abundance with redshift. However, the sample size and the low statistics associated with most of the clusters in the sample prevents us to draw any statistically significant conclusion on the different evolutionary path that the different regions of the clusters may have traversed. 
Alessandro Baldi, Stefano Ettori, Silvano Molendi, Italo Balestra,   Fabio Gastaldello, Paolo Tozzi
astro-ph.CO