Moore Christopher J, Finch Eliot, Buscicchio Riccardo, Gerosa Davide
School of Physics and Astronomy & Institute for Gravitational Wave Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
iScience. 2021 Jun 16;24(6):102577. doi: 10.1016/j.isci.2021.102577. eCollection 2021 Jun 25.
Gravitational-wave observations of binary black holes allow new tests of general relativity (GR) to be performed on strong, dynamical gravitational fields. These tests require accurate waveform models of the gravitational-wave signal; otherwise waveform errors can erroneously suggest evidence for new physics. Existing waveforms are generally thought to be accurate enough for current observations, and each of the events observed to date appears to be individually consistent with GR. In the near future, with larger gravitational-wave catalogs, it will be possible to perform more stringent tests of gravity by analyzing large numbers of events together. However, there is a danger that waveform errors can accumulate among events: even if the waveform model is accurate enough for each individual event, it can still yield erroneous evidence for new physics when applied to a large catalog. This paper presents a simple linearized analysis, in the style of a Fisher matrix calculation that reveals the conditions under which the apparent evidence for new physics due to waveform errors grows as the catalog size increases. We estimate that, in the worst-case scenario, evidence for a deviation from GR might appear in some tests using a catalog containing as few as events above a signal-to-noise ratio of 20. This is close to the size of current catalogs and highlights the need for caution when performing these sorts of experiments.
双黑洞的引力波观测使得在强动态引力场中对广义相对论（GR）进行新的测试成为可能。这些测试需要引力波信号的精确波形模型；否则，波形误差可能会错误地暗示新物理的证据。现有波形通常被认为对于当前观测足够精确，并且迄今为止观测到的每个事件似乎都与广义相对论单独一致。在不久的将来，随着更大的引力波目录的出现，通过一起分析大量事件，将有可能对引力进行更严格的测试。然而，存在一个风险，即波形误差可能在事件之间累积：即使波形模型对于每个单独事件足够精确，但当应用于大型目录时，它仍可能产生新物理的错误证据。本文提出了一种简单的线性化分析，采用费希尔矩阵计算的方式，揭示了由于波形误差导致的新物理的明显证据随着目录大小增加而增长的条件。我们估计，在最坏的情况下，在一些使用信噪比高于20且包含少至 个事件的目录的测试中，可能会出现偏离广义相对论的证据。这接近当前目录的大小，并突出了进行此类实验时需要谨慎的必要性。
