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arXiv 0812.2264astro-ph
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Cyg X-2中沿Z方向扩展吸积盘日冕的加热

Heating in an Extended Accretion Disk Corona along the Z-Pattern in Cyg X-2

N. S. Schulz, D. P. Huenemoerder, L. Ji, M. Nowak, Y. Yao, C. R. Canizares

摘要:

我们在非常高的光谱分辨率下观察了原型Z源Cyg x-2两次沿其整个X射线光谱变化模式。在这个初步的分析中,我们发现一个扩展的吸积盘电晕表现出莱曼α发射从各种H-类离子,以及发射从He-类离子的Fe和Al,和Li-类离子的Fe。最亮的谱线显示出谱线加宽的范围:类H谱线非常宽,多普勒速度在1100至2700 km/s之间,而其他一些谱线则较窄,宽度为几百km/s。线诊断允许我们第一次确定冠状参数。这些谱线的性质与一个稳定的、延伸到10^10 cm、致密(1 × 10^15 cm^-3)和热(log xi > 3; T > 10^6 K)的吸积盘日冕相一致。我们发现正在进行加热的日冕沿Z-轨道,并确定加热光度从约0.4 L_Edd的水平变化到约1.4 L_Edd的耀斑分支。

英文摘要:

We observed at very high spectral resolution the prototype Z-source Cyg x-2 twice along its entire X-ray spectral variation pattern. In this preliminary analysis we find an extended accretion disk corona exhibiting Lyman alpha emissions from various H-like ions, as well as emissions from He-like ions of Fe and Al, and Li-like ions of Fe. The brightest lines show a range of line broadening: H-like lines are very broad with Doppler velocities between 1100 and 2700 km/s, while some others are narrower with widths of a few hundred km/s. Line diagnostics allow us for the first time to determine coronal parameters. The line properties are consistent with a stationary, extended up to 10^10 cm, dense (1x10^15 cm^-3), and hot (log xi > 3; T > 10^6 K) accretion disk corona. We find ongoing heating of the corona along the Z-track and determine that heating luminosities change from about 0.4 L_Edd on the horizontal to about 1.4 L_Edd on the flaring branch.

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