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McDonald, M.; Bulbul, E.; Haan, T. de; Miller, E. D.; Benson, B. A.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chiu, I.; Forman, W. R.; Hlavacek-Larrondo, J.; Garmire, G. P.; Gupta, N.; Mohr, J. J.; Reichardt, C. L.; Saro, A.; Stalder, B.; Stark, A. A. and Vieira, J. D. (2016): The evolution of the intracluster medium metallicity in Sunyaev Zel'dovich-selected galaxy clusters at 0 <z < 1.5. In: Astrophysical Journal, Vol. 826, No. 2, 124

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We present the results of an X-ray spectral analysis of 153 galaxy clusters observed with the Chandra, XMM-Newton, and Suzaku space telescopes. These clusters, which span 0 < z < 1.5, were drawn from a larger, mass-selected sample of galaxy clusters discovered in the 2500 square degree South Pole Telescope Sunyaev Zel'dovich (SPT-SZ) survey. With a total combined exposure time of 9.1 Ms, these data yield the strongest constraints to date on the evolution of the metal content of the intracluster medium (ICM). We find no evidence for strong evolution in the global (r < R-500) ICM metallicity (dZ/dz = -0.06 +/- 0.04 Z(circle dot)), with a mean value at z = 0.6 of < Z > = 0.23 +/- 0.01 Z(circle dot) and a scatter of sigma Z = 0.08 +/- 0.01 Z(circle dot). These results imply that the emission-weighted metallicity has not changed by more than 40% since z = 1 (at 95% confidence), consistent with the picture of an early (z > 1) enrichment. We find, in agreement with previous works, a significantly higher mean value for the metallicity in the centers of cool core clusters versus non-cool core clusters. We find weak evidence for evolution in the central metallicity of cool core clusters (dZ/dz = -0.21 +/- 0.11 Z(circle dot)), which is sufficient to account for this enhanced central metallicity over the past similar to 10 Gyr. We find no evidence for metallicity evolution outside of the core (dZ/dz = -0.03 +/- 0.06 Z(circle dot)), and no significant difference in the core-excised metallicity between cool core and non-cool core clusters. This suggests that strong radio-mode active galactic nucleus feedback does not significantly alter the distribution of metals at r > 0.15R(500). Given the limitations of current-generation X-ray telescopes in constraining the ICM metallicity at z > 1, significant improvements on this work will likely require next-generation X-ray missions.

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