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arXiv 2301.08946astro-ph.HE
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加热或冷却:光学薄平流主导吸积流流入和流出的对流热输送研究

Heating or Cooling: Study of Advective Heat Transport in the Inflow and the Outflow of Optically Thin Advection-dominated Accretion Flows

Cheng-Liang Jiao

摘要:

平流被认为是光学薄平流为主的吸积流(ADAF)的主要冷却机制。然而,当考虑流出时,第一印象是,由于径向运动的方向相反,平流在流入和流出中应具有相反的符号。那么如何同时实现能量平衡呢?我们调查的问题,在本文中,分析的配置文件的不同组成部分的平流与自相似的解决方案ADAF的球坐标系($rθϕ$)。我们发现,对于$n < 3γ/2-1$,其中$n$是密度指数在$ρ\propto r^{-n}$和$γ$是热容比,径向平流是一个加热机制的流入和冷却机制的流出。对于$n = 3γ/2-1$,它变为0,对于$n > 3γ/2-1$,它变为流入中的冷却机制和流出中的加热机制。能量守恒仅在考虑纬向($θ$ -方向)平流时实现,该平流取适当的值以维持能量平衡,使得平流的总体效果,无论参数选择如何,始终是抵消各处粘性加热的冷却机制。对于$n=3/2$的极端情况,纬向运动停止,粘性加热仅由径向平流平衡,没有外流。

英文摘要:

Advection is believed to be the dominant cooling mechanism in optically thin advection-dominated accretion flows (ADAF's). When outflow is considered, however, the first impression is that advection should be of opposite sign in the inflow and the outflow, due to the opposite direction of radial motion. Then how is the energy balance achieved simultaneously? We investigate the problem in this paper, analysing the profiles of different components of advection with self-similar solutions of ADAF's in spherical coordinates ($rθϕ$). We find that for $n < 3γ/2-1$, where $n$ is the density index in $ρ\propto r^{-n}$ and $γ$ is the heat capacity ratio, the radial advection is a heating mechanism in the inflow and a cooling mechanism in the outflow. It becomes 0 for $n = 3γ/2-1$, and turns to a cooling mechanism in the inflow and a heating mechanism in the outflow for $n > 3γ/2-1$. The energy conservation is only achieved when the latitudinal ($θ$-direction) advection is considered, which takes an appropriate value to maintain energy balance, so that the overall effect of advection, no matter the parameter choices, is always a cooling mechanism that cancels out the viscous heating everywhere. For the extreme case of $n=3/2$, latitudinal motion stops, viscous heating is balanced solely by radial advection, and no outflow is developed.

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。

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