发表机构
Max-Planck-Institut für Radioastronomie; Monash University; OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery; Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut); Leibniz Universität Hannover; Jodrell Bank Centre for Astrophysics, University of Manchester（马克斯·普朗克射电天文研究所; 莫纳什大学; 引力波发现ARC卓越中心; 马克斯·普朗克引力物理研究所（爱因斯坦研究所）; 汉诺威莱布尼茨大学; 曼彻斯特大学乔德雷尔银行天体物理学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种仅基于相位测量探测纳赫兹引力波背景的新方法，无需准重采样即可避免误检，并通过模拟数据验证了其能有效恢复谱参数。
AI 中文摘要
明确探测脉冲星计时数据中的引力波背景（GWB）需要稳健的探测统计量。脉冲星计时领域目前严重依赖基于互相关的“最优统计量”。其设计初衷是避免未建模的脉冲星红噪声导致的误检。然而，van Haasteren（2025）最近的研究表明，最优统计量实际上并非最优。此外，最优统计量仍易受噪声模型错误设定导致的误检影响。为防范此问题，分析人员采用准重采样方法，如相位平移，即对每个脉冲星应变测量值随机分配复数相位，从而破坏任何引力波引起的相关性。受相位平移概念的启发，我们引入了一种形式体系，其中GWB完全通过相位测量来探测。我们认为，该方法无需临时准重采样方法即可对误检具有稳健性。我们通过测量注入到简化模拟脉冲星计时阵列数据集中的模拟GWB的振幅和谱指数，证明了该形式体系的可行性。在此示例中，我们使用基于模拟的推断，并用神经圆形样条流对基于相位的似然函数进行建模。我们表明，使用基于相位的似然函数能够充分恢复引力波背景信号的谱参数。通过将我们的结果与最优统计量获得的结果进行比较，我们展示了振幅与相位各自贡献了多少分辨能力。
英文摘要
Unambiguously detecting a gravitational-wave background (GWB) in pulsar-timing data requires a robust detection statistic. The pulsar timing community currently relies heavily on the cross-correlation-based "optimal statistic." Its design was motivated to avoid false-positive detections from unmodeled pulsar red noise. However, recent work by van Haasteren (2025) suggests that the optimal statistic is not, in fact, optimal. Moreover, the optimal statistic is still susceptible to false positives from misspecified noise. To guard against this, analysts employ quasi-resampling methods such as phase shifts, in which complex phases are randomly assigned to each pulsar strain measurement, thereby destroying any gravitational-wave-induced correlations. Inspired by the concept of phase shifts, we introduce a formalism in which the GWB is measured entirely from phase measurements. We argue that this approach is robust against false positive detections without the need for ad hoc quasi-resampling methods. We demonstrate the feasibility of this formalism by measuring the amplitude and spectral index of a simulated GWB, injected to a simplified mock representation of a pulsar timing array data set. For this example, we use simulation-based-inference and model the phase-based likelihood using a neural circular spline flow. We show that it is possible to adequately recover the spectral parameters of the gravitational wave background signal using the phase-based likelihood. By comparing our results to ones obtained with the optimal statistic, we show how much resolving power comes from amplitude versus phase.
Comments8+3 (appendix) pages, 9 figures. Under review with Astronomy & Astrophysics
