An analytic toy model for relativistic accretion in Kerr space–time
An analytic toy model for relativistic accretion in Kerr space–time
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DOI：
10.1093/mnras/sts316
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发表时间：
2012-07
影响因子：
4.8
通讯作者：
Emilio Tejeda;P. Taylor;J. Miller
中科院分区：
文献类型：
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作者：
Emilio Tejeda;P. Taylor;J. Miller
我们提出了一个相对论性模型，描述了一个非相互作用粒子落在克尔黑洞上的旋转云的稳态轴对称吸积流。基于弹道近似，流线解析描述的类时测地线，而一个简单的数值计算方案的密度场。提出了一种新的方法，通过一个单一的解析表达式来描述所有可能的轨道类型。这个模型是一个有用的工具，突出纯粹的相对论签名吸积流动力学来自一个强大的引力场与帧拖动。特别是，我们探讨了由于这之间的黑洞的自旋和角动量的下落物质的耦合。此外，我们演示了如何将此解析解用于基准广义相对论数值流体动力学代码，通过将其与光滑粒子流体动力学模拟的结果进行比较，以获得一个类似的设置。这些模拟首先进行弹道流（零压力），然后为流体动力学的，我们测量的压力梯度的影响，从而探索弹道近似的适用范围。
We present a relativistic model for the stationary axisymmetric accretion flow of a rotating cloud of non-interacting particles falling onto a Kerr black hole. Based on a ballistic approximation, streamlines are described analytically in terms of timelike geodesics, while a simple numerical scheme is introduced for calculating the density field. A novel approach is presented for describing all of the possible types of orbit by means of a single analytic expression. This model is a useful tool for highlighting purely relativistic signatures in the accretion flow dynamics coming from a strong gravitational field with frame-dragging. In particular, we explore the coupling due to this between the spin of the black hole and the angular momentum of the infalling matter. Moreover, we demonstrate how this analytic solution may be used for benchmarking general relativistic numerical hydrodynamics codes by comparing it against results of smoothed particle hydrodynamics simulations for a collapsar-like setup. These simulations are performed first for a ballistic flow (with zero pressure) and then for a hydrodynamical one where we measure the effects of pressure gradients on the infall, thus exploring the extent of applicability of the ballistic approximation.