Copi Craig, Starkman Glenn D
Department of Physics/CERCA/ISO, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom.
Phys Rev Lett. 2022 Jun 24;128(25):251101. doi: 10.1103/PhysRevLett.128.251101.
Observations of a merging neutron star binary in both gravitational waves, by the Laser Interferometer Gravitational-Wave Observatory (LIGO), and across the spectrum of electromagnetic radiation, by myriad telescopes, have been used to show that gravitational waves travel in vacuum at a speed that is indistinguishable from that of light to within one part in a quadrillion. However, it has long been expected mathematically that, when electromagnetic or gravitational waves travel through vacuum in a curved spacetime, the waves develop tails that travel more slowly. The associated signal has been thought to be undetectably weak. Here we demonstrate that gravitational waves are efficiently scattered by the curvature sourced by ordinary compact objects-stars, white dwarfs, neutron stars, and planets-and certain candidates for dark matter, populating the interior of the null cone. The resulting gravitational glint should imminently be detectable, and be recognizable (for all but planets) as briefly delayed echoes of the primary signal emanating from extremely near the direction of the primary source. This opens the prospect for using Gravitational Detection and Ranging to map the Universe and conduct a comprehensive census of massive compact objects, and ultimately to explore their interiors.
激光干涉引力波天文台（LIGO）对一对合并中的中子星双星进行的引力波观测，以及众多望远镜对其全电磁辐射频谱的观测，已被用于表明引力波在真空中的传播速度与光速相差不到千万亿分之一，几乎无法区分。然而，长期以来从数学上就预期，当电磁或引力波在弯曲时空中的真空中传播时，波会产生传播速度较慢的尾波。相关信号被认为微弱到无法探测。在此我们证明，引力波会被普通致密天体（恒星、白矮星、中子星和行星）以及某些暗物质候选体所产生的曲率有效散射，这些天体分布在零锥内部。由此产生的引力闪烁应该很快就能被探测到，并且（除行星外）可以被识别为来自主源方向极近处的主信号的短暂延迟回波。这为利用引力探测与测距来绘制宇宙地图、对大质量致密天体进行全面普查，并最终探索其内部结构开辟了前景。
