Simulating the emission and outflows from accretion discs
Simulating the emission and outflows from accretion discs
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DOI：
10.1088/0264-9381/24/12/s17
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发表时间：
2007-01
影响因子：
3.5
通讯作者：
S. Noble;P. Leung;C. Gammie;L. Book
中科院分区：
文献类型：
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作者：
S. Noble;P. Leung;C. Gammie;L. Book
射电源人马座 A* (Sgr A*) 被认为是一种热的、不均匀的磁化等离子体，在银河系中心 3.6 × 106 M⊙ 黑洞的事件视界附近流动。从角度大小来看，距离为 8 kpc（≃ 2.5 × 1022 厘米）的黑洞将是最大的黑洞之一。最近的观察结果与毫米和亚毫米光子主要由光学薄的热同步加速器发射主导的观点是一致的。预计未来在这些波长下对 Sgr A* 进行甚长基线干涉测量 (VLBI) 观测，我们在此提出了第一个基于吸积流的一般相对论数值模拟的 Sgr A* 毫米和亚毫米发射的动态自洽模型。假设重子温度下的电子热分布由模拟和吸积率决定，计算与角度相关的光谱，吸积率在我们的模型中充当自由参数。显示了不同模型参数（黑洞自旋和自旋与视线的倾斜度）和源变化对光谱的影响。我们发现，将计算的毫米通量与观测到的通量相匹配所需的吸积率值与从旋转测量的检测推断出的吸积率的约束一致。我们还描述了吸积盘沿黑洞自旋轴发射的相对论性喷流，并演化到~103GMc−2的尺度，其中M是黑洞的质量。
The radio source Sagittarius A* (Sgr A*) is believed to be a hot, inhomogeneous, magnetized plasma flowing near the event horizon of the 3.6 × 106 M⊙ black hole at the galactic centre. At a distance of 8 kpc (≃ 2.5 × 1022 cm) the black hole would be among the largest black holes as judged by angular size. Recent observations are consistent with the idea that the millimetre and sub-millimetre photons are dominated by optically thin, thermal synchrotron emission. Anticipating future Very Long Baseline Interferometry (VLBI) observations of Sgr A* at these wavelengths, we present here the first dynamically self-consistent models of millimetre and sub-millimetre emission from Sgr A* based on general relativistic numerical simulations of the accretion flow. Angle-dependent spectra are calculated assuming a thermal distribution of electrons at the baryonic temperature dictated by the simulation and the accretion rate, which acts as a free parameter in our model. The effects of varying model parameters (black hole spin and inclination of the spin to the line of sight) and source variability on the spectrum are shown. We find that the accretion rate value needed to match our calculated millimetre flux to the observed flux is consistent with constraints on the accretion rate inferred from detections of the rotation measure. We also describe the relativistic jet that is launched along the black hole spin axis by the accretion disc and evolves to scales of ∼103GMc−2, where M is the mass of the black hole.