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Toward connecting core-collapse supernova theory with observations.

机译：试图将核塌陷超新星理论与观测联系起来。

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摘要

We study the evolution of the collapsing core of a 15 solar mass blue supergiant supernova progenitor from the moment shortly after core bounce until 1.5 seconds later. We present a sample of two- and three-dimensional hydrodynamic models parameterized to match the explosion energetics of supernova SN 1987A. We focus on the characteristics of the flow inside the gain region and the interplay between hydrodynamics, self-gravity, and neutrino heating, taking into account uncertainty in the nuclear equation of state.;We characterize the evolution and structure of the flow behind the shock in terms the accretion flow dynamics, shock perturbations, energy transport and neutrino heating effects, and convective and turbulent motions. We also analyze information provided by particle tracers embedded in the flow. Our models are computed with a high-resolution finite volume shock capturing hydrodynamic code. The code includes source terms due to neutrino-matter interactions from a light-bulb neutrino scheme that is used to prescribe the luminosities and energies of the neutrinos emerging from the core of the proto-neutron star. The proto-neutron star is excised from the computational domain, and its contraction is modeled by a time-dependent inner boundary condition.;We find the spatial dimensionality of the models to be an important contributing factor in the explosion process. Compared to two-dimensional simulations, our three-dimensional models require lower neutrino luminosities to produce equally energetic explosions. We estimate that the convective engine in our models is 4% more efficient in three dimensions than in two dimensions. We propose that this is due to the difference of morphology of convection between two- and three-dimensional models. Specifically, the greater efficiency of the convective engine found in three-dimensional simulations might be due to the larger surface-to-volume ratio of convective plumes, which aids in distributing energy deposited by neutrinos.;We do not find evidence of the standing accretion shock instability in our models. Instead we identify a relatively long phase of quasi-steady convection below the shock, driven by neutrino heating. During this phase, the analysis of the energy transport in the post-shock region reveals characteristics closely resembling that of penetrative convection. We find that the flow structure grows from small scales and organizes into large, convective plumes on the size of the gain region.;We use tracer particles to study the flow properties, and find substantial differences in residency times of fluid elements in the gain region between two-dimensional and three-dimensional models. These appear to originate at the base of the gain region and are due to differences in the structure of convection. We also identify differences in the evolution of energy of the fluid elements, how they are heated by neutrinos, and how they become gravitationally unbound. In particular, at the time when the explosion commences, we find that the unbound material has relatively long residency times in two-dimensional models, while in three dimensions a significant fraction of the explosion energy is carried by particles with relatively short residency times.;We conduct a series of numerical experiments in which we methodically decrease the angular resolution in our three-dimensional models. We observe that the explosion energy decreases dramatically once the resolution is inadequate to capture the morphology of convection on large scales. Thus, we demonstrated that it is possible to connect successful, energetic, three-dimensional models with unsuccessful three-dimensional models just by decreasing numerical resolution, and thus the amount of resolved physics. This example shows that the role of dimensionality is secondary to correctly accounting for the basic physics of the explosion.;The relatively low spatial resolution of current three-dimensional models allows for only rudimentary insights into the role of turbulence in driving the explosion. However, and contrary to some recent reports, we do not find evidence for turbulence being a key factor in reviving the stalled supernova shock.
机译：我们研究了15个太阳质量蓝色超巨型超新星祖先坍缩的核从核反弹后的瞬间到1.5秒后的演化。我们提出了一个二维和三维流体动力学模型的样本，这些模型参数化以匹配超新星SN 1987A的爆炸能量。考虑到核态方程的不确定性，我们着重研究增益区内的流动特性以及流体力学，自重和中微子加热之间的相互作用。我们表征了激波背后的流动演变和结构。就吸积流动力学，冲击扰动，能量传输和中微子加热效应以及对流和湍流运动而言。我们还分析了嵌入到流中的粒子示踪剂提供的信息。我们的模型是用高分辨率的有限体积冲击捕获流体力学代码计算的。该代码包括源术语，这是由于来自灯泡中微子方案的中微子与物质之间的相互作用而产生的，该术语被用来规定从原中子星核心产生的中微子的光度和能量。从计算域中切除原中子星，并通过与时间相关的内部边界条件对它的收缩进行建模。；我们发现模型的空间维是爆炸过程中的重要因素。与二维模拟相比，我们的三维模型需要较低的中微子发光度才能产生同样高能的爆炸。我们估计模型中的对流引擎在三个维度上的效率比在两个维度上的效率高4％。我们认为这是由于二维和三维模型之间的对流形态不同所致。具体来说，在三维模拟中发现的对流发动机效率更高，可能是由于对流羽流的表面积与体积之比较大，这有助于分配中微子沉积的能量。模型中的冲击不稳定性。相反，我们确定了在中微子加热的作用下，冲击之下准稳态对流的相对较长阶段。在此阶段，对震后区域能量传输的分析显示出与穿透对流非常相似的特征。我们发现流动结构从小规模开始增长，并在增益区域的大小上组织成大的对流羽状流;;我们使用示踪粒子研究流动特性，并发现增益区域中流体元素的停留时间存在实质性差异在二维和三维模型之间。这些似乎起源于增益区域的底部，并且是由于对流结构的差异。我们还确定了流体元素的能量演化，中微子如何加热以及它们如何变得不受重力约束的差异。特别是，在爆炸开始时，我们发现在二维模型中未结合的物质具有相对较长的停留时间，而在三维中，爆炸能量的很大一部分是由停留时间相对较短的粒子携带的。我们进行了一系列数值实验，其中我们有条不紊地降低了三维模型中的角分辨率。我们观察到，一旦分辨率不足以大规模捕获对流形态，爆炸能量就会急剧下降。因此，我们证明了仅通过降低数值分辨率，从而减少已解决的物理量，就可以将成功的，充满活力的三维模型与不成功的三维模型连接起来。此示例表明，维的作用在正确解释爆炸的基本物理作用之后是次要的。当前三维模型的相对较低的空间分辨率仅能基本了解湍流在推动爆炸中的作用。但是，与最近的一些报道相反，我们没有找到证据证明湍流是使停滞的超新星电击得以恢复的关键因素。

著录项

  • 作者

    Handy, Timothy A.;

  • 作者单位

    The Florida State University.;

  • 授予单位 The Florida State University.;
  • 学科 Physics Astrophysics.;Mathematics.;Computer Science.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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