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首页> 外文期刊>The Astrophysical journal >Disk-dominated States Of 4u 1957+11: Chandra, Xmm-newton, And Rxte Observations Of Ostensibly The Most Rapidly Spinning Galactic Black Hole
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Disk-dominated States Of 4u 1957+11: Chandra, Xmm-newton, And Rxte Observations Of Ostensibly The Most Rapidly Spinning Galactic Black Hole

机译：4u 1957 + 11年的磁盘主导状态：Chandra，Xmm-newton和Rxte观测到的表面上最快速旋转的银河黑洞

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We present simultaneous Chandra High-Energy Transmission Gratings (HETG) and Rossi X-ray Timing Explorer (RXTE) observations of a "soft state" of the black hole candidate 4U 1957+11. These spectra, having limited hard X-ray excess, are an excellent test of disk atmosphere models that include effects of black hole spin. The HETG data show, by modeling the broadband continuum and direct fitting of absorption edges, that the disk spectrum is only very mildly absorbed, with N_H = (1-2)×10~(21) cm~(-2). These data additionally reveal λλ13.449 Ne Ⅸ absorption consistent with the warm/hot phase of the interstellar medium. The fitted disk model implies an inclined disk around a low-mass black hole rotating with normalized spin a~* ≈ 1. We show, however, that pure Schwarzschild models describe the data extremely well, albeit with large disk atmosphere "color-correction" factors. Standard correction factors can be attained if one incorporates mild Comptonization. We find that the Chandra observations do not uniquely determine spin, even with this otherwise extremely well-measured, nearly pure disk spectrum. XMM-Newton RXTE observations, taken only six weeks later, are equally unconstraining. This lack of constraint is partly driven by the unknown mass and distance of 4U 1957+11; however, it is also driven by the limited Chandra and XMM-Newton bandpasses. We therefore present a series of 48 RXTE observations taken at different brightness/hardness levels. These data prefer a spin of a~*≈ 1, even when including a mild Comptonization component; however, they also show evolution of the color-correction factors. If the rapid-spin models with standard correction factors are to be believed, then the RXTE observations predict that 4U 1957+11 can range from a 3 M_☉ black hole at 10kpc with a* ≈ 0.83 to a 16 M_☉ black hole at 22 kpc with a~* ≈ 1.
机译：我们同时提出了钱德拉高能透射光栅（HETG）和罗西X射线定时资源管理器（RXTE）对黑洞候选4U 1957 + 11的“软状态”的观察。这些具有有限的硬X射线过量的光谱，是对包括黑洞旋转效应的磁盘气氛模型的出色测试。 HETG数据通过对宽带连续区进行建模并直接拟合吸收边缘，表明圆盘光谱仅被非常轻微地吸收，N_H =（1-2）×10〜（21）cm〜（-2）。这些数据还揭示了与星际介质的暖/热相一致的λλ13.449NeⅨ吸收。拟合的磁盘模型意味着围绕低质量黑洞的倾斜磁盘，该黑洞以归一化自旋a〜*≈1旋转。但是，我们证明，尽管具有较大的磁盘气氛“色彩校正”，但是纯Schwarzschild模型对数据的描述非常好。因素。如果将温和的Comptonization纳入其中，则可以达到标准的校正因子。我们发现，钱德拉的观测结果并不能唯一地确定自旋，即使采用这种方法，其测量也非常好，几乎是纯磁盘光谱。仅在六个星期后进行的XMM-Newton RXTE观测同样不受约束。这种缺乏约束的部分原因是4U 1957 + 11的质量和距离未知。但是，它也受有限的Chandra和XMM-Newton带通驱动。因此，我们提出了在不同亮度/硬度水平下进行的一系列48次RXTE观测。这些数据更喜欢旋转a〜*≈1，即使包含温和的Comptonization分量也是如此。但是，它们也显示了色彩校正因子的演变。如果可以相信具有标准校正因子的快速旋转模型，那么RXTE观测结果预测4U 1957 + 11的范围可以从10kpc的3M_☉黑洞（a *≈0.83）到22 M的16M_☉黑洞。 kpc的a〜*≈1。

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