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arXiv 1004.3592astro-ph.GA
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NGC 4472的热ISM中的异常模式:见解和异常

The Abundance Pattern in the Hot ISM of NGC 4472: Insights and Anomalies

Michael Loewenstein, David Davis

摘要:

椭圆星系的化学和动力学历史的重要线索编码在X射线发射等离子体中的重元素丰度。通过对朱雀星光谱的分析,并结合同空间XMM-牛顿谱的分析,我们得到了NGC 4472内外区的热ISM丰度分布。朱雀XIS探测器的低背景和相对尖锐的光谱分辨率,结合NGC 4472的高光度和温度,使我们能够推导出一个特别广泛的丰度模式,包括O,Ne,Mg,Al,Si,S,Ar,Ca,Fe和Ni。我们应用简单的化学演化模型,这些数据,并得出结论,最好的解释相结合的α-元素增强恒星质量损失和直接注入Ia型超新星(SNIa)喷出物的丰度。因此,我们证实了推断,根据光学数据,在椭圆星系的恒星有超太阳α/Fe比,但发现,目前的SNIa率是4-6倍低于标准值。我们发现SNIa产量集,复制Ca和Ar,或Ni,但不是所有三个同时。相对于Ne和Mg,O的丰度较低,这意味着标准的核心坍缩核合成模型过量产生O的因子为2。

英文摘要:

Important clues to the chemical and dynamical history of elliptical galaxies are encoded in the abundances of heavy elements in the X-ray emitting plasma. We derive the hot ISM abundance pattern in inner and outer regions of NGC 4472 from analysis of Suzaku spectra, supported by analysis of co-spatial XMM-Newton spectra. The low background and relatively sharp spectral resolution of the Suzaku XIS detectors, combined with the high luminosity and temperature in NGC 4472, enable us to derive a particularly extensive abundance pattern that encompasses O, Ne, Mg, Al, Si, S, Ar, Ca, Fe, and Ni in both regions. We apply simple chemical evolution models to these data, and conclude that the abundances are best explained by a combination of alpha-element enhanced stellar mass loss and direct injection of Type Ia supernova (SNIa) ejecta. We thus confirm the inference, based on optical data, that the stars in elliptical galaxies have supersolar alpha/Fe ratios, but find that that the present-day SNIa rate is 4-6 times lower than the standard value. We find SNIa yield sets that reproduce Ca and Ar, or Ni, but not all three simultaneously. The low abundance of O relative to Ne and Mg implies that standard core collapse nucleosynthesis models overproduce O by a factor of 2.

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