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.
