CHEERS：化学演变RGS样品
CHEERS: The chemical evolution RGS sample
摘要：
超新星的化学产额和热的星团内介质（ICM）的金属富集还没有得到很好的理解。本文介绍了用XMM-牛顿观测到的44个明亮的局域巨椭圆星系、星系群和星系团的化学富集RGS样品（CHEERS）。利用反射光栅光谱仪（RGS）对大气中O和Fe的丰度进行了测量。深度曝光和样品的大小使我们能够量化的内在散射和系统的不确定性，在丰度使用光谱建模技术。我们报告的氧和铁的丰度与RGS在样品中的所有对象的核心区域测量。我们没有发现一个显着的趋势，O/Fe作为集群温度的函数，但我们确实发现了一个内在的分散在O和Fe丰度从集群集群。O/Fe比值的系统不确定性水平估计约为20- 30%，而O和Fe绝对丰度的系统不确定性在极端情况下可高达50%。我们能够识别和纠正系统的偏差，在氧丰度测定，这是由于光谱模型的不准确性。O/Fe对温度的依赖性的缺乏表明，ICM的富集不依赖于集群的质量，大部分的富集可能发生在ICM形成之前。我们发现，所观察到的分散在O/Fe比是由于组合的内在散射源和系统的光谱拟合的不确定性，我们无法解开。内在散射的天体物理学来源可能是由于活动星系核活动的差异和BCG中正在进行的恒星形成。系统散射是由于空间谱线展宽、吸收柱、多温度结构和热等离子体模型的不确定性造成的。（略）。
英文摘要：
The chemical yields of supernovae and the metal enrichment of the hot intra-cluster medium (ICM) are not well understood. This paper introduces the CHEmical Enrichment RGS Sample (CHEERS), which is a sample of 44 bright local giant ellipticals, groups and clusters of galaxies observed with XMM-Newton. This paper focuses on the abundance measurements of O and Fe using the reflection grating spectrometer (RGS). The deep exposures and the size of the sample allow us to quantify the intrinsic scatter and the systematic uncertainties in the abundances using spectral modeling techniques. We report the oxygen and iron abundances as measured with RGS in the core regions of all objects in the sample. We do not find a significant trend of O/Fe as a function of cluster temperature, but we do find an intrinsic scatter in the O and Fe abundances from cluster to cluster. The level of systematic uncertainties in the O/Fe ratio is estimated to be around 20-30%, while the systematic uncertainties in the absolute O and Fe abundances can be as high as 50% in extreme cases. We were able to identify and correct a systematic bias in the oxygen abundance determination, which was due to an inaccuracy in the spectral model. The lack of dependence of O/Fe on temperature suggests that the enrichment of the ICM does not depend on cluster mass and that most of the enrichment likely took place before the ICM was formed. We find that the observed scatter in the O/Fe ratio is due to a combination of intrinsic scatter in the source and systematic uncertainties in the spectral fitting, which we are unable to disentangle. The astrophysical source of intrinsic scatter could be due to differences in AGN activity and ongoing star formation in the BCG. The systematic scatter is due to uncertainties in the spatial line broadening, absorption column, multi-temperature structure and the thermal plasma models. (Abbreviated).
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