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arXiv 2203.05050astro-ph.GA
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中心质量为BH的二分量星系模型中的多方Bondi吸积

On the polytropic Bondi accretion in two-component galaxy models with a central massive BH

Antonio Mancino, Luca Ciotti, Silvia Pellegrini

摘要:

在许多涉及中心质点吸积的研究中,从观测研究到宇宙学模拟,包括半解析建模,经典的Bondi吸积理论是广泛采用的标准工具。以前的工作概括了该理论,包括星系的引力场的影响,托管一个中央黑洞,和电子散射的光学薄的限制。在这里,我们将这个扩展的邦迪问题,在一般多变的情况下,最近提出的一类新的两个组件的星系模型。在这些模型中,一个贾菲恒星密度分布嵌入在暗物质晕,使总密度分布遵循$r^{-3}$配置文件在大半径的恒星动力学量可以表示在一个完全解析的方式。流动的流体动力学性质是通过强加气体温度在无穷远是成比例的恒星组件的维里温度。等温和绝热(单原子)的情况下,可以解析地解决,在其他情况下,我们探索的吸积解决方案的数值。由于非绝热吸积不可避免地导致与环境的热交换,我们还讨论了多方Bondi吸积的一些重要的物理性质,并提供了计算与环境交换的热量所需的表达式,作为半径的函数。所得结果可为数值模拟中吸积的亚网格处理和观测资料的解释提供参考。

英文摘要:

In many investigations involving accretion on a central point mass, ranging from observational studies to cosmological simulations, including semi-analytical modelling, the classical Bondi accretion theory is the standard tool widely adopted. Previous works generalised the theory to include the effects of the gravitational field of the galaxy hosting a central black hole, and of electron scattering in the optically thin limit. Here we apply this extended Bondi problem, in the general polytropic case, to a class of new two-component galaxy models recently presented. In these models, a Jaffe stellar density profile is embedded in a dark matter halo such that the total density distribution follows a $r^{-3}$ profile at large radii; the stellar dynamical quantities can be expressed in a fully analytical way. The hydrodynamical properties of the flow are set by imposing that the gas temperature at infinity is proportional to the virial temperature of the stellar component. The isothermal and adiabatic (monoatomic) cases can be solved analytically, in the other cases we explore the accretion solution numerically. As non-adiabatic accretion inevitably leads to an exchange of heat with the ambient, we also discuss some important thermodynamical properties of the polytropic Bondi accretion, and provide the expressions needed to compute the amount of heat exchanged with the environment, as a function of radius. The results can be useful for the subgrid treatment of accretion in numerical simulations, as well as for the interpretation of observational data.

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