On the evolution of rapidly rotating massive white dwarfs towards supernovae or collapses
On the evolution of rapidly rotating massive white dwarfs towards supernovae or collapses
复制标题
DOI：
10.1051/0004-6361:20042542
复制
发表时间：
2005-02
影响因子：
6.5
通讯作者：
Sung-Chul Yoon;N. Langer
中科院分区：
文献类型：
--
作者：
Sung-Chul Yoon;N. Langer
最近的一项研究表明，快速增长的(M>；10-7M0.Y_r~(-1)CO白矮星可能会有差动旋转，其切变命运在动力切变不稳定开始的阈值附近。这种差异旋转的白矮星具有热核爆炸或电子俘获引起的崩塌的临界质量，大大超过了正则钱德拉塞卡极限。在这里，我们构造了二维微分旋转白矮星模型，其旋转规律类似于以前工作中的一维模型。我们推导出了白矮星质量、角动量、转动能、引力能和束缚能之间的解析关系。结果表明，这些关系式适用于包括固体自转在内的各种角速度分布。在中心密度为2×10~9g·cm~(-3)时，它们给出了旋转CO白矮星热核爆炸的初始模型。在ρc=1010g cm-3和4×109g cm-3时，分别给出了电子俘获诱导的旋转CO和OneMg白矮星崩塌的判据。我们的工作很好地建立了刚性旋转和差动旋转白矮星的爆炸前和坍塌前条件，这将有助于未来对La型超新星爆炸的多维模拟，以及从坍塌的白矮星形成毫秒脉冲星和伽马射线爆发的研究。我们的结果使我们对la超新星类型的祖先提出了各种可能的进化情景，导致了一种新的白矮星爆炸质量的新范例，其值远远高于经典的钱德拉塞卡质量。基于我们的2D模型，我们认为超新星的峰值亮度与白矮星质量成正比，这可以解释LA型超新星多样性的各个方面，如亮度的变化，其平均光度与宿主星系类型的关系，以及抛射速度和峰值亮度之间的弱相关性。
A recent study indicated that the inner cores of rapidly accreting (M > 10 -7 M ○. yr -1 ) CO white dwarfs may rotate differentially, with a shear fate near the threshold value for the onset of the dynamical shear instability. Such differentially rotating white dwarfs have critical masses for thermonuclear explosion or electron-capture induced collapse that significantly exceed the canonical Chandrasekhar limit. Here, we construct two-dimensional differentially rotating white dwarf models with rotation laws resembling those of the one-dimensional models of the previous work. We derive analytic relations between the white dwarf mass, its angular momentum, and its rotational-, gravitational- and binding energy. We show that these relations are applicable for a wide range of angular velocity profiles, including solid body rotation. Taken at a central density of 2 x 10 9 g cm -3 they specify initial models for the thermonuclear explosion of rotating CO white dwarfs. At ρ c = 10 10 g cm -3 and 4 x 10 9 g cm -3 , they give criteria for the electron-capture induced collapse of rotating CO and ONeMg white dwarfs, respectively. We demonstrate that pre-explosion and pre-collapse conditions of both rigidly and differentially rotating white dwarfs are well established by the present work, which may facilitate future multi-dimensional simulations of type la supernova explosions and studies of the formation of millisecond pulsars and gamma-ray bursts from collapsing white dwarfs. Our results lead us to suggest various possible evolutionary scenarios for progenitors of type la supernovae, leading to a new paradigm of a variable mass of exploding white dwarfs, at values well above the classical Chandrasekhar mass. Based on our 2D-models, we argue that the supernova peak brightness is proportional to the white dwarf mass, which could explain various aspects of the diversity of type la supernovae, such as their variation in brightness, the dependence of their mean luminosity on the host galaxy type, and the weak correlation between ejecta velocity and peak brightness.