Probing the Nanohertz Gravitational Wave Background

AST0206044PI Backer来自远距离时钟的电磁脉冲穿过引力波，根据发射器和接收器处的引力波相位的不同，会经历可变的延迟。这一效应允许使用最精确的脉冲星的空间阵列，这些脉冲星是精密的天文时钟，作为灵敏的重力波探测器，在非常低的nhz频率下，使用持续数年的测量间隔。预计应该会有一个低频的随机引力辐射背景，作为宇宙形成早期的遗迹，但来自星系核中大质量黑洞双星合并的具有天体物理意义的引力波的前景将是nhz频率的主要来源。由选定脉冲星组成的全球脉冲星定时阵列对引力辐射的正探测至关重要，它涉及阿雷西博实验、新的绿岸望远镜的继续和改进，以及与法国阿姆斯特丹和澳大利亚的脉冲星小组合作，为多脉冲星/多频率/多望远镜分析收集“最佳”组合数据集。该项目还将了解脉冲星的内在属性和脉冲星视线内等离子体的湍流结构。*

AST 0206044PI BackerElectromagnetic pulses from a distant clock traversing a gravitational wave experience a variable delay depending on the gravitational wave phase at the emitter and at the receiver. This effect allows the use of a spatial array of the most precise pulsars, which are precision celestial clocks, as a sensitive gravity-wave detector at very low, nHz, frequencies using a measurement interval extending over several years. It is expected there should be a low frequency random background of gravitational radiation as a relic from an early epoch of the formation of the Universe, but that an astrophysically significant 'foreground' of gravity waves from the coalescence of massive black hole binaries in the nuclei of galaxies will be the dominant source at nHz frequencies. The global Pulsar Timing Array of selected pulsars is essential for positive detection of gravitational radiation and involves a continuation and improvement of the Arecibo experiments, the new Green Bank Telescope, and a collaboration with pulsar groups in Amsterdam, France, and Australia to assemble the "best" combined data sets for the multi-pulsar/multi-frequency/multi-telescope analysis. The project will also learn about the intrinsic properties of pulsars and the turbulence structure of the plasma in the line of sight to the pulsar.***