论文标题

一种新的流体动力球形积分精确溶液及其准球面扰动

A new hydrodynamic spherical accretion exact solution and its quasi-spherical perturbations

论文作者

Hernandez, X., Nasser, L., Aguayo-Ortiz, A.

论文摘要

我们提出了一个精确的$γ= 5/3 $球形积聚解决方案,该解决方案将$ρ\ $ρ\ $ r \ to $ r \ to \ infty $至$ρ\ to $ρ\ to 0 $ to $ r \ to $ r \ to \ infty $修改$ρ\ $ρ\ $ρ\ $ρ\ $ρ\。这种变化允许在密度和插入速度场上简单的功率法解决方案,范围从压力趋于零的冷空自由落体条件到无插入速度的热静水平衡极限。与邦迪溶液一样,出现了最大积聚率。就像在邦迪解决方案的$γ= 5/3 $情况下一样,没有出现声音半径,这一次,因为流程始终以恒定的马赫数为特征。对于最大吸积率的情况,该数字等于1,在冷空状态下发散,并向静水平衡极限变为亚音线。可以证明,在{$ r \至0 $}的极限中,邦迪解决方案趋向于提出的新解决方案,{扩展邦德增生值的有效性}}情况下,在}情况下,积聚密度曲线并未保持固定的恒定值保持在无限限。然后,我们通过分析性扰动分析探索与球形和角动量存在的小偏差。这种扰动的溶液通过Legendre多项式来通过密度和速度场产生丰富的现象学,我们开始探索,对于简单的角速度边界条件,在平面和极点上具有零。提出的新解决方案总体上为积聚问题提供了互补的物理洞察力。

We present an exact $γ=5/3$ spherical accretion solution which modifies the Bondi boundary condition of $ρ\to const.$ as $r\to \infty$ to $ρ\to 0$ as $r \to \infty$. This change allows for simple power law solutions on the density and infall velocity fields, ranging from a cold empty free-fall condition where pressure tends to zero, to a hot hydrostatic equilibrium limit with no infall velocity. As in the case of the Bondi solution, a maximum accretion rate appears. As in the $γ=5/3$ case of the Bondi solution, no sonic radius appears, this time however, because the flow is always characterised by a constant Mach number. This number equals 1 for the case of the maximum accretion rate, diverges towards the cold empty state, and becomes subsonic towards the hydrostatic equilibrium limit. It can be shown that in the limit as { $r \to 0$}, the Bondi solution tends to the new solution presented, { extending the validity of the Bondi accretion value to} cases where the accretion density profile does not remain at a fixed constant value out to infinity. We then explore small deviations from sphericity and the presence of angular momentum through an analytic perturbative analysis. Such perturbed solutions yield a rich phenomenology through density and velocity fields in terms of Legendre polynomials, which we begin to explore for simple angular velocity boundary conditions having zeros on the plane and pole. The new solution presented provides complementary physical insight into accretion problems in general.

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