Dissecting X-ray–Emitting Gas Around the Center of Our Galaxy
Dissecting X-ray–Emitting Gas Around the Center of Our Galaxy
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DOI：
10.1126/science.1240755
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发表时间：
2013-07
期刊：
影响因子：
56.9
通讯作者：
Q. Wang;Q. Wang;M. Nowak;S. Markoff;F. Baganoff;S. Nayakshin;F. Yuan;J. Cuadra;John E. Davis-John-E.-Dav
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文献类型：
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作者：
Q. Wang;Q. Wang;M. Nowak;S. Markoff;F. Baganoff;S. Nayakshin;F. Yuan;J. Cuadra;John E. Davis-John-E.-Dav
X射线中的银河系中心在我们银河系的中心有一个黑洞，质量比太阳大400万倍。Wang等人（第981页;参见Schnittman的《透视》）报告了这个超大质量黑洞周围吸积流的X射线数据，揭示了它如何与周围环境相互作用。这些数据排除了观测到的静止（即无耀斑）x射线是由银河系中心恒星群的日冕发射产生的可能性，也排除了存在没有流出的纯辐射低效吸积流的可能性。对银河系中心的X射线观测揭示了那里的大质量黑洞与其周围环境之间的相互作用。[Also大多数超大质量黑洞（SMBH）的吸积水平非常低，很难与它们所在的星系中心区分开来。我们自己的银河系的SMBH提供了一个有启发性的例外，我们提出了一个近距离观察其静态X射线发射的基础上3兆秒的钱德拉观测。虽然X射线辐射是拉长的，并且与周围的大质量恒星盘很好地对齐，但我们可以排除低质量日冕活动恒星的聚集作为辐射的来源，因为缺乏预测的铁（Fe）Kα辐射。极弱的类氢Fe Kα线进一步表明存在从吸积流到SMBH的流出。这些结果提供了重要的约束模型的普遍辐射低效吸积状态。
The Galaxy Center in X-rays At the center of our Galaxy there is a black hole 4-million-fold more massive than the Sun. Wang et al. (p. 981; see the Perspective by Schnittman) report x-ray data on the accretion flow around this supermassive black hole, revealing how it interacts with its surroundings. The data rule out the possibility that the quiescent (that is, flare-free) x-rays observed are produced by coronal emission from a population of stars at the center of the Galaxy and also rule out the possibility that there is a pure radiatively inefficient accretion flow with no outflows. X-ray observations of the center of our Galaxy reveal the interplay between the massive black hole there and its surroundings. [Also see Perspective by Schnittman] Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy’s SMBH provides an instructive exception, and we present a close-up view of its quiescent x-ray emission based on 3 megaseconds of Chandra observations. Although the x-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission on the basis of the lack of predicted iron (Fe) Kα emission. The extremely weak hydrogen (H)–like Fe Kα line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.