Searching for Outflows in Ultraluminous X-ray Sources Through High-Resolution X-ray Spectroscopy
Searching for Outflows in Ultraluminous X-ray Sources Through High-Resolution X-ray Spectroscopy
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DOI：
10.1093/mnras/stx2695
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发表时间：
2017-10
影响因子：
4.8
通讯作者：
P. Kosec;C. Pinto;A. Fabian;D. Walton
中科院分区：
文献类型：
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作者：
P. Kosec;C. Pinto;A. Fabian;D. Walton
超铝X射线源是一种非核点源，其亮度超过10个太阳质量黑洞的爱丁顿光度。对于大多数ULX人口的现代共识是，它们是由恒星质量的黑洞或中子星吸积远远超过爱丁顿极限提供动力的。超爱丁顿吸积的理论模型预测存在强大的流出适度电离气体在温和的相对论速度。到目前为止，这些风已经在3个系统中发现：NGC 1313 X-1，NGC 5408 X-1，NGC 55 ULX。在这项工作中，我们创建了一个样本的所有ULX与可用的档案高分辨率X射线数据，共有10个来源，我们的目标是找到更多的签名流出。我们执行高斯线扫描以找到任何窄光谱特征，并在可能的情况下进行物理风模型扫描。我们初步确定在NGC 5204 X-1流出，蓝移到0.34 c，产生的排放功能，总的显着性至少为3 $\sigma $。接下来，我们比较具有相似硬度比的ULX。Holmberg IX X-1的吸收特征可能与光电离的外流吸收体有关，类似于NGC 1313 X-1。Holmberg II X-1的光谱具有与NGC 5408 X-1相似的特征，NGC 6946 X-1显示O VIII静止帧发射。来自样本的所有其他来源也在其高分辨率光谱中显示出光谱特征的初步证据。使用XMM-牛顿和钱德拉光栅的进一步观测将产生更强的约束。像XARM和雅典娜这样的未来任务将能够在更远的距离上探测到它们，并增加我们的样本。
Ultraluminous X-ray sources are non-nuclear point sources exceeding the Eddington luminosity of a 10 Solar mass black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or neutron stars accreting well above the Eddington limit. Theoretical models of super-Eddington accretion predict existence of powerful outflows of moderately ionised gas at mildly relativistic velocities. So far, these winds have been found in 3 systems: NGC 1313 X-1, NGC 5408 X-1, NGC 55 ULX. In this work, we create a sample of all ULXs with usable archival high resolution X-ray data, with 10 sources in total, in which we aim to find more signatures of outflows. We perform Gaussian line scans to find any narrow spectral signatures, and physical wind model scans where possible. We tentatively identify an outflow in NGC 5204 X-1, blueshifted to 0.34c, which produces emission features with a total significance of at least 3$\sigma$. Next we compare ULXs with similar hardness ratios. Holmberg IX X-1 shows absorption features which could be associated with a photoionized outflowing absorber, similar to that seen in NGC 1313 X-1. The spectrum of Holmberg II X-1 possesses features similar to NGC 5408 X-1 and NGC 6946 X-1 shows O VIII rest-frame emission. All other sources from the sample also show tentative evidence of spectral features in their high resolution spectra. Further observations with the XMM-Newton and Chandra gratings will place stronger constraints. Future missions like XARM and Athena will be able to detect them at larger distances and increase our sample.