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arXiv 1012.3144gr-qcastro-ph.COhep-phhep-th
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替代引力理论中的有效引力波应力-能量张量

Effective Gravitational Wave Stress-energy Tensor in Alternative Theories of Gravity

Leo C. Stein, Nicolas Yunes

摘要:

真空中双星系统的内旋受引力辐射的应力能和其他传播自由度的控制。对于引力波,主要贡献的特点是在未来零无穷大的有效应力能量张量。我们采用微扰理论和短波长近似计算这种应力-能量张量在广泛的替代理论。我们发现,这个张量通常是修改的第一次计算的艾萨克森,其中的修正可以支配广义相对论项。然而,在许多理论中,这些修正在渐近平坦的、未来的、零无穷大处完全消失,使应力-能量张量变成艾萨克森的。我们首先考虑动力学的陈-西蒙斯修正引力,它通过一个标量场和黎曼张量及其对偶的收缩来纠正这种作用,从而解释了这种现象。然后,我们考虑一类广泛的理论与动力学标量场耦合到高阶曲率不变量,并表明,引力波应力-能量张量仍然减少到艾萨克森的。本文的计算对于通过双星轨道衰变或通过引力波观测系统地检验这种修正的引力理论是至关重要的。

英文摘要:

The inspiral of binary systems in vacuum is controlled by the stress-energy of gravitational radiation and any other propagating degrees of freedom. For gravitational waves, the dominant contribution is characterized by an effective stress-energy tensor at future null infinity. We employ perturbation theory and the short-wavelength approximation to compute this stress-energy tensor in a wide class of alternative theories. We find that this tensor is generally a modification of that first computed by Isaacson, where the corrections can dominate over the general relativistic term. In a wide class of theories, however, these corrections identically vanish at asymptotically flat, future, null infinity, reducing the stress-energy tensor to Isaacson's. We exemplify this phenomenon by first considering dynamical Chern-Simons modified gravity, which corrects the action via a scalar field and the contraction of the Riemann tensor and its dual. We then consider a wide class of theories with dynamical scalar fields coupled to higher-order curvature invariants, and show that the gravitational wave stress-energy tensor still reduces to Isaacson's. The calculations presented in this paper are crucial to perform systematic tests of such modified gravity theories through the orbital decay of binary pulsars or through gravitational wave observations.

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