Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows
Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows
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超音速吸积流中非球形扰动增长的线性分析
DOI：
10.1088/0004-637x/794/2/162
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Kazuya Takahashi & Shoichi Yamada
中科院分区：
文献类型：
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作者：
Taisuke Ohshima;Tomohiro Tachi;Hiroya Tanaka;Yasushi Yamaguchi;Yuki Hiruta Mikiko Ishikawa;Kazuya Takahashi & Shoichi Yamada
我们分析了超音速吸积流中非球形扰动的增长。我们想到了一个应用程序的核心坍缩超新星（CCSNe）的反弹后阶段。这种非球形扰动已经在阿内特的一系列论文中提出，他用数值方法研究了坍缩前恒星外层的剧烈对流。此外，考奇和奥特在他们的数值模拟中证明，这种扰动可能会导致一个成功的超新星，即使是一个没有波动而未能爆炸的祖先。本文研究了失速激波在入射过程中扰动的线性增长。线性化的方程组作为一个初始和边界值问题与使用的拉普拉斯变换。背景是一个Bondi吸积流，其参数被选择为模仿Woosley & Heger的15 M吸积祖先模型，该模型被认为是CCSNe的典型祖先。我们发现，在大半径处给出的扰动随着它们向下流动到激波半径而增长;例如，密度扰动可以放大30倍。我们分析表明，增长率是成比例的l，球谐函数的指数。我们还发现，扰动振荡的频率是类似的那些常设吸积激波不稳定性的时间。这可能对CCSNe中的激波复活有影响，我们将在即将发表的论文中对此进行更详细的研究。
We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch & Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solved as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M☉ progenitor model by Woosley & Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.