关于吸积盘粘性各向同性的研究
On the isotropy of viscosity in accretion discs
AI总结：
本文通过X射线双星的长期观测，检验Ogilvie模型对吸积盘演化描述的准确性，发现粘性可能存在轻微非各向同性特征。
摘要：
吸积盘是许多天体系统中的核心部分，通过将引力势能转化为辐射能量。许多系统中存在盘形变的证据，从原行星盘的空间分辨观测到超大质量黑洞周围盘的光变曲线和谱线特征。 warped盘的动力学主要由内部粘性物理性质控制。虽然通常粘性源于流体磁性，但磁化盘的模拟无法匹配平面盘的角动量输运速率，因此无法确定驱动吸积和盘形变的扭矩比例。Ogilvie的解析工作是最全面的warped盘演化模型，但其假设需要检验。特别是，它假设盘粘性为纳维-斯托克斯，因此是小尺度且各向同性的。本文尝试通过X射线双星的长期观测来检验该模型，这些系统有良好的粘性成分估计，通过有无盘偏移和进动证据的系统，可以约束使盘扁平化的粘性成分。我们得出结论，观测约束表明Ogilvie模型对盘演化有充分描述，但存在粘性可能略微非各向同性的迹象。
英文摘要：
Accretion discs are fundamental to many astrophysical systems, providing the conversion of gravitational potential energy into radiation that we can observe. In many systems there is evidence that discs are warped; from spatially-resolved observations of protoplanetary discs, to the features of lightcurves and line profiles from discs around supermassive black holes in galaxy centres. The dynamics of warped discs is largely controlled by the physical nature of the internal disc viscosity. While typically disc viscosity is hydromagnetic in origin, simulations of magnetized discs cannot match observed rates of angular momentum transport in planar discs and thus cannot be used to determine the ratio of the torques responsible for driving accretion to those responsible for evolving the disc warp. The analytic work of Ogilvie is the most comprehensive model for warped disc evolution, but makes assumptions that need to be tested. In particular, it assumes that the disc viscosity is Navier-Stokes, and therefore small-scale and isotropic. Here we attempt to test this model using the long periods of X-ray binaries that are due to precession of the disc. These systems have well-constrained estimates of the component of viscosity responsible for driving accretion, and by looking at systems with and without evidence for disc misalignment and precession we can constrain the component of viscosity responsible for flattening the disc. We conclude that the observational constraints suggest that the Ogilvie model provides an adequate description of the disc evolution, but that there are indications that the internal disc viscosity might be marginally non-isotropic.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
