Evolution in the Iron Abundance of the ICM(Chapter 3. Chemical Structure and Evolution Clusters of Galaxy, The Extreme Universe in the Suzaku Era)

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概要

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• We present a Chandra analysis of the X-ray spectra of 56 clusters of galaxies at z>0.3, which cover a temperature range of 3>kT>15keV. Our analysis is aimed at measuring the iron abundance in the ICM out to the highest redshift probed to date. We find that the emission-weighted iron abundance measured within (0.15-0.3) R_<vir> in clusters below 5keV is, on average, a factor of〜2 higher than in hotter clusters, following Z(T)≃0.88T^<-0.47>Z_&029BF;, which confirms the trend seen in local samples. We made use of combined spectral analysis performed over five redshift bins at 0.3>z>1.3 to estimate the average emission weighted iron abundance. We find a constant average iron abundance Z_<Fe>≃0.25Z_&029BF as a function of redshift, but only for clusters at z>0.5. The emission-weighted iron abundance is significantly higher (Z_<Fe>≃0.4Z_&029BF) in the redshift range z≃0.3-0.5, approaching the value measured locally in the inner 0.15 R_<vir> radii for a mix of cool-core and non cool-core clusters in the redshift range 0.1<z<0.3. The decrease in Z_<Fe> with z can be parametrized by a power law of the form〜(1+z)^<-1.25>. The observed evolution implies that the average iron content of the ICM at the present epoch is a factor of〜2 larger than at z≃1.2. We confirm that the ICM is already significantly enriched (Z_<Fe>≃0.25Z_&029BF) at a look-back time of 9Gyr. Our data provide significant constraints on the time scales and physical processes that drive the chemical enrichment of the ICM.

• 理論物理学刊行会の論文
• 2007-12-19

著者

• Norman Colin

  European Southern Observatory:department Of Physics And Astronomy Johns Hopkins University

• Tozzi Paolo

  Inaf Osservatorio Astronomico

• Rosati Piero

  European Southern Observatory

• BALESTRA Italo

  Max-Planck-Institut fur Extraterrestrische Physik

• TOZZI Paolo

  INAF, Osservatorio Astronomico di Trieste

• ETTORI Stefano

  INAF, Osservatorio Astronomico di Bologna

• BORGANI Stefano

  INAF, Osservatorio Astronomico di Trieste

• MAINIERI Vincenzo

  Max-Planck-Institut fur Extraterrestrische Physik

• BALESTRA Italo

  MPE

• Borgani Stefano

  Inaf Osservatorio Astronomico Di Trieste:infn National Institute For Nuclear Physics:dipartimento Di

• Mainieri Vincenzo

  Max-planck-institut Fur Extraterrestrische Physik:european Southern Observatory

• NORMAN Colin

  European Southern Observatory:Department of Physics and Astronomy, Johns Hopkins University

• ETTORI Stefano

  INAF, Osservatorio Astronomico

• BORGANI Stefano

  INAF, Osservatorio Astronomico di Trieste:INFN, National Institute for Nuclear Physics:Dipartimento di Astronomia dell'Universita di Trieste

• Tozzi Paolo

  INAF, Osservatorio Astronomico

関連論文

• The Cluster Gas Mass Fraction as a Cosmological Probe : a Revised Study(Chapter 2. Thermal Structure/Dynamics of Groups and Clusters of Galaxies, The Extreme Universe in the Suzaku Era)
• Evolution in the Iron Abundance of the ICM(Chapter 3. Chemical Structure and Evolution Clusters of Galaxy, The Extreme Universe in the Suzaku Era)

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