Relativistic Gravitation and Astrophysics

在未来十年内，从天体物理学来源可能探测到的引力波将为天文学打开一扇新的窗户，并为爱因斯坦的广义相对论提供新的检验。 解释观测结果需要根据理论计算出精确的理论重力波形。这个项目将奋进通过在后牛顿近似下系统地求解爱因斯坦方程来提供超声波波形，这相当于v/c的幂次展开，其中v和c分别是源体和光速。我们的目标是找到超越牛顿引力的（v/c）7阶的天体运动方程，以及超越最低“四极”近似的（v/c）6阶的引力辐射通量。这将利用一种方法称为直接积分的放松爱因斯坦方程（DIRE），已开发的华盛顿大学。利用这种方法，也将有可能研究物体的内部结构，包括它们的自旋，对运动和引力波形的影响，达到后牛顿膨胀的高阶。还将研究如何利用引力波数据来检验引力的替代理论。这包括通过观测中子星的引力波进入黑洞来检验标量-张量替代理论，以及通过使用拟议的天基引力天线丽莎观测超大质量黑洞对的引力波来检验引力子是否具有质量。最近发表的一类预测大质量引力子的引力替代理论将被详细研究，作为“陪衬”，与广义相对论的预测进行比较和对比，并作为对大质量引力子的其他可能测试的指导。

Within the next decade the likely detection of gravitational waves from astrophysicalsources will open a new window for astronomy and provide new tests of Einstein's theoryof general relativity. Interpreting the observations will require accurate theoretical gravi-tational waveforms calculated from the theory. This project will endeavor to provide theneeded waveforms, by solving Einstein's equations systematically in a post-Newtonian ap-proximation, which amounts to an expansion in powers of v/c, where v and c are the speedsof the source bodies and of light, respectively. The goal will be to find the equations ofmotion for the bodies correct to order (v/c)7 beyond Newtonian gravity, and the flux ofgravitational radiation to order (v/c)6 beyond the lowest "quadrupole" approximation. Thiswill make use of a method known as Direct Integration of the Relaxed Einstein Equations(DIRE), that has been developed at Washington University. Using this method it will alsobe possible to study the effects of the interior structure of the bodies, including their spin,on the motion and gravitational waveform, to high order in the post-Newtonian expansion.Ways to use gravitational-wave data to test alternative theories of gravity will also bestudied. This includes testing the scalar-tensor alternative theories by observing gravita-tional waves from neutron stars inspiralling into black holes, and testing whether or not thegraviton has a mass by observing waves from inspiral of pairs of supermassive black holesusing the proposed space-based gravitational antenna, LISA. A recently published class ofalternative theories of gravity that predict a massive graviton will be studied in detail as"foils" against which to compare and contrast the predictions of general relativity, and asguides to other possible tests of a massive graviton.