Coalescing neutron stars: A Step towards physical models. 1: Hydrodynamic evolution and gravitational wave emission
Coalescing neutron stars: A Step towards physical models. 1: Hydrodynamic evolution and gravitational wave emission
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聚结中子星：迈向物理模型的一步。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
G. Schaefer
中科院分区：
文献类型：
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作者：
M. Ruffert;H. Janka;G. Schaefer
我们研究了聚结中子星的动力学和演化。虽然程序(分段抛物线方法)是纯牛顿的，但我们确实包括了引力波的发射及其对流体动力流动的反向反应。中子星物质的性质用拉蒂默-斯威斯蒂(1991)的物理状态方程来描述。一个精细的“中微子泄漏方案”考虑了所有类型中微子的能量损失以及电子中微子和反中微子的发射引起的电子分数的变化。我们模拟了两颗重子质量约为1.6，半径约为15，初始中心距为42公里，重子质量约为1.6，半径约为15 mm的冷中子星的合并过程。根据流体静力平衡(中心温度约为8 MeV)的冷中子星模型给出了密度和电子浓度的初始分布。我们研究了中子星初始速度分布不同的三种情况，它们代表了中子星相对于轨道角动量矢量方向自转的不同情况。在大约1~ms的时间内，中子星合并成一个快速自转(P_rm自旋约1~ms)的高密度天体(约10^{14}~g/cm~3$)，周围有一个密度约为10^{10}~10^{12}~g/cm~3$的物质盘，轨道速度约为0.3~0.5℃。在即将发表的一篇论文中，我们将集中讨论中微子的发射及其对伽马射线暴的影响。在大约1~ms的时间内，最大发光度超过$10^{55}$~erg/S。
We investigate the dynamics and evolution of coalescing neutron stars. Although the code (Piecewise Parabolic Method) is purely Newtonian, we do include the emission of gravitational waves and their backreaction on the hydrodynamic flow. The properties of neutron star matter are described by the physical equation of state of Lattimer \& Swesty (1991). Energy loss by all types of neutrinos and changes of the electron fraction due to the emission of electron neutrinos and antineutrinos are taken into account by an elaborate ``neutrino leakage scheme''. We simulate the coalescence of two identical, cool neutron stars with a baryonic mass of $\approx\!1.6\,M_\odot$ and a radius of $\approx\!15$~km and with an initial center-to-center distance of 42~km. The initial distributions of density and electron concentration are given from a model of a cold neutron star in hydrostatic equilibrium (central temperature about $8\,{\rm MeV}$). We investigate three cases which differ by the initial velocity distribution in the neutron stars, representing different cases of the neutron star spins relative to the direction of the orbital angular momentum vector. Within about 1~ms the neutron stars merge into a rapidly spinning ($P_{\rm spin}\approx 1$~ms), high-density body ($\rho\approx 10^{14}$~g/cm$^3$) with a surrounding thick disk of material with densities $\rho\approx 10^{10}-10^{12}$~g/cm$^3$ and orbital velocities of~0.3--0.5~c. In this work we evaluate the models in detail with respect to the gravitational wave emission using the quadrupole approximation. In a forthcoming paper we will concentrate on the neutrino emission and implications for gamma-ray bursters. A maximum luminosity in excess of $10^{55}$~erg/s is reached for about 1~ms.