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arXiv 0709.4499astro-ph
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M87中的富金属多相气体：活动星系核驱动的金属输运，磁场支持的多温气体，以及用XMM-牛顿观测到的非热发射的约束

Metal-rich multi-phase gas in M87: AGN-driven metal transport, magnetic-field supported multi-temperature gas, and constraints on non-thermal emission observed with XMM-Newton

A. Simionescu, N. Werner, A. Finoguenov, H. Boehringer, M. Brueggen

备注：
18 pages, accepted for publication in A&A. Some significant changes following the referee report
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摘要：

我们使用深（~120 ks）XMM-牛顿数据的M87晕，分析其空间分辨的温度结构和化学成分。我们特别关注与内射电瓣相关的X射线亮度增强的区域，这些区域已知不能很好地由单温度谱模型描述。与简单的两温度拟合相比，我们使用涉及每个空间箱中连续温度范围的模型获得了更好和更物理的光谱描述。多相气体的温度范围跨越~0.6-3.2 keV。这种多相结构只有在热传导被磁场抑制时才是可能的。在多温区，我们发现了比周围X射线等离子体更冷的气体的量与金属丰度之间的相关性，并得出结论，冷气体比周围的晕更富含金属。我们估计冷气体的平均Fe丰度约为2.2太阳。因此，我们的研究结果指向的关键作用的活动星系核（AGN）在运输重元素到集群内的介质。的O/Si/S/Fe的丰度比和外部的X射线臂是相似的，表明在气体晕中的金属的主要部分被抬升的活动星系核爆发相对较近的年龄M87。我们估计冷气体的质量为5e 8 M_sun，这可能是ICM、恒星质量损失和Ia型超新星产物的混合物。在冷气体中产生所观察到的金属需要约30-110百万年。最后，我们对M87可能的非热X射线发射提出了上限，并将其与90厘米射电图相结合，我们对磁场强度提出了约0.5-1.0 μ G的下限。

英文摘要：

We use deep (~120 ks) XMM-Newton data of the M87 halo to analyze its spatially resolved temperature structure and chemical composition. We focus particularly on the regions of enhanced X-ray brightness associated with the inner radio lobes, which are known not to be described very well by single-temperature spectral models. Compared to a simple two-temperature fit, we obtain a better and more physical description of the spectra using a model that involves a continuous range of temperatures in each spatial bin. The range of temperatures of the multiphase gas spans ~0.6-3.2 keV. Such a multiphase structure is only possible if thermal conduction is suppressed by magnetic fields. In the multi-temperature regions, we find a correlation between the amount of gas cooler than the surrounding X-ray plasma and the metallicity, and conclude that the cool gas is more metal-rich than the ambient halo. We estimate the average Fe abundance of the cool gas to ~2.2 solar. Our results thus point toward the key role of the active galactic nucleus (AGN) in transporting heavy elements into the intracluster medium. The abundance ratios of O/Si/S/Fe in and outside the X-ray arms are similar, indicating that the dominant fraction of metals in the gas halo was uplifted by AGN outbursts relatively recently compared to the age of M87. Our estimate for the mass of the cool gas is 5e8 M_sun, which probably stems from a mixture of ICM, stellar mass loss, and Type Ia supernova products. ~30-110 Myr are required to produce the observed metals in the cool gas. Finally, we put upper limits on possible non-thermal X-ray emission from M87 and, combining it with the 90 cm radio maps, we put lower limits of around ~0.5-1.0 muG on the magnetic field strength.

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