标题： 无旋双中子星的演化序列 显示英文标题

标题： Evolutionary sequences of irrotational binary neutron stars

摘要： 我们展示了零涡度双中子星准平衡序列的数值计算结果，在广义相对论框架下。 爱因斯坦方程在共形平坦的空间3-度规（Wilson-Mathews近似）假设下求解。 随着轨道由于引力波发射而收缩，每个恒星的中心密度演化被监测。 对于紧致化比 M/R = 0.14，中心密度在减小之前保持相当稳定（轻微增加，低于 0.1%）。 对于更高的紧致化比 M/R = 0.17（即更接近最大质量配置的恒星），在密度下降前观察到非常小的密度增加（最多 0.3%）。 此效应仍在共形平坦近似的误差范围内。 因此可以得出结论，没有发现恒星的实质性压缩，这可能表明它们在合并前没有倾向于单独塌缩成黑洞。 此外，在演化序列中未发现结合能或角动量的拐点，这可能意味着这些系统不存在最内层稳定圆轨道（ISCO）。 显示英文摘要

摘要： We present results of numerical computations of quasiequilibrium sequences of binary neutron stars with zero vorticity, in the general relativistic framework. The Einstein equations are solved under the assumption of a conformally flat spatial 3-metric (Wilson-Mathews approximation). The evolution of the central density of each star is monitored as the orbit shrinks in response to gravitational wave emission. For a compactification ratio M/R=0.14, the central density remains rather constant (with a slight increase, below 0.1%) before decreasing. For a higher compactification ratio M/R=0.17 (i.e. stars closer to the maximum mass configuration), a very small density increase (at most 0.3%) is observed before the decrease. This effect remains within the error induced by the conformally flat approximation. It can be thus concluded that no substantial compression of the stars is found, which would have indicated a tendency to individually collapse to black hole prior to merger. Moreover, no turning point has been found in the binding energy or angular momentum along evolutionary sequences, which may indicate that these systems do not have any innermost stable circular orbit (ISCO).