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arXiv 1210.0874astro-ph.HE
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用Chandra和XMM-牛顿法测量ADC源X1822-371的X射线光谱

X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

R. Iaria, T. Di Salvo, A. D'Aì, L. Burderi, T. Mineo, A. Riggio, A. Papitto, N. R. Robba

摘要:

食源低质量X射线双星X 1822 -371是吸积盘日冕源的原型。我们分析了两个钱德拉观测和一个XMM-牛顿观测研究的离散功能和它们的变化作为轨道相位的函数,推导出的温度,密度和位置的等离子体负责发射线的约束。HETGS和XMM/Epic-pn分别在140和50 ks时观察到X1822-371。我们从五个选定的轨道相位间隔中提取了一个平均光谱和五个光谱,它们是0.04-0.25,0.25-0.50,0.50-0.75,0.75-0.95,最后是0.95-1.04;轨道相位零对应于日食时间。所有的光谱覆盖的能带之间的0.35和12千电子伏。我们确认存在局部中性物质,部分覆盖的X射线发射区;等效氢柱为$5 \times 10^{22}$ cm $ ^{-2}$和覆盖分数约为60- 65%。我们确定从高度电离的元素的发射线,和一个突出的荧光铁线与FeI-FeXV共振跃迁的混合。类氦离子的跃迁表明,相互作用对禁戒线和共振线起主导作用。在0.04和0.75之间的轨道相位期间,线通量最高。我们讨论了存在一个扩展的,光学薄电晕的光学深度约为0.01,散射的X射线光子从最里面的区域进入视线。产生大部分观察到的谱线的光电离等离子体被放置在圆盘外半径处的凸起中,距离中心源$6 \times 10^{10}$ cm。OVII和荧光铁线可能是在光盘的内半径的光电离表面。(节录)

英文摘要:

The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. We analyse two Chandra observations and one XMM-Newton observation to study the discrete features and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectra from five selected orbital-phase intervals that are 0.04-0.25, 0.25-0.50, 0.50-0.75, 0.75-0.95, and, finally, 0.95-1.04; the orbital phase zero corresponds to the eclipse time. All spectra cover the energy band between 0.35 and 12 keV. We confirm the presence of local neutral matter that partially covers the X-ray emitting region; the equivalent hydrogen column is $5 \times 10^{22}$ cm$ ^{-2}$ and the covered fraction is about 60-65%. We identify emission lines from highly ionised elements, and a prominent fluorescence iron line associated with a blending of FeI-FeXV resonant transitions. The transitions of He-like ions show that the intercombination dominates over the forbidden and resonance lines. The line fluxes are the highest during the orbital phases between 0.04 and 0.75. We discuss the presence of an extended, optically thin corona with optical depth of about 0.01 that scatters the X-ray photons from the innermost region into the line of sight. The photoionised plasma producing most of the observed lines is placed in the bulge at the outer radius of the disc distant from the central source of $6 \times 10^{10}$ cm. The OVII and the fluorescence iron line are probably produced in the photoionised surface of the disc at inner radii. (Abridged)

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