[论文解读] Theoretical Physics Implications of the Binary Black-Hole Merger GW150914

Nicolás Yunes, Kent Yagi+1 more|arXiv (Cornell University)|Mar 29, 2016

Pulsars and Gravitational Waves Research被引用 12

一句话总结

本文分析了引力波事件GW150914，以约束非标准引力物理，包括修正引力理论、标量场、额外维度以及奇异致密天体。结果表明，GW150914为强场引力提供直接探测，显著收紧了广义相对论偏离的约束，尤其是在引力波传播和黑洞替代模型方面。

ABSTRACT

The gravitational-wave observation GW150914 by Advanced LIGO provides the first opportunity to learn about physics in the extreme gravity of coalescing binary black holes. The LIGO/Virgo collaboration has verified that this observation is consistent with General Relativity, constraining the presence of parametric anomalies in the signal. This paper expands this analysis to a larger class of anomalies, highlighting the inferences that can be drawn on non-standard theoretical physics mechanisms that would affect the signal. We find that GW150914 constrains a plethora of mechanisms associated with the generation and propagation of gravitational waves, including the activation of scalar fields, gravitational leakage into large extra dimensions, the variability of Newton's constant, the speed of gravity, a modified dispersion relation, gravitational Lorentz violation and the strong equivalence principle. Unlike other observations that limit these mechanisms, GW150914 is a direct probe of dynamical strong-field gravity and gravitational wave propagation. We also show that GW150914 constrains the properties of exotic compact object alternatives to Kerr black holes. The true potential for GW150914 to both constrain exotic objects and physics beyond General Relativity is limited by the lack of understanding of the dynamical strong field in almost all modified gravity theories. GW150914 thus raises the bar that these theories must pass, both in terms of having a sound theoretical underpinning, and the minimal level to which the corresponding equations of motion must be solved in binary coalescences. We conclude with a discussion of additional inferences that can be drawn from smaller-confidence observations, such as the LVT151012 trigger and electromagnetic counterparts to GW150914, the latter of which would produce dramatic constraints on the speed of gravity and gravitational Lorentz violation.

研究动机与目标

• 研究GW150914对广义相对论之外非标准引力物理的影响。
• 评估观测到的引力波信号如何约束影响引力波生成与传播的机制。
• 评估奇异致密天体模型作为Kerr黑洞替代方案的可行性。
• 强调需要改进修正引力理论中的理论框架，以准确匹配强场双星并合动力学。
• 探讨来自低显著性事件（如LVT151012）以及GW150914潜在电磁对应体的额外约束。

提出的方法

• 分析超越标准LIGO/Virgo检验，通过考察GW150914信号中更广泛的参数异常类别。
• 将从观测波形中获得的约束应用于涉及标量场、可变牛顿常数和修正色散关系的理论模型。
• 评估引力向大额外维度泄漏以及洛伦兹不变性与等效原理强形式的破坏。
• 利用GW150914相位与振幅中未观测到偏离的事实，排除或限制引力波传播中的奇异机制。
• 将奇异致密天体的理论模型与GW150914观测到的铃荡与并合动力学进行对比评估。
• 本文讨论了若检测到电磁对应体，将如何进一步约束引力传播速度与洛伦兹破坏。

实验结果

研究问题

• RQ1 在强场区域，GW150914在多大程度上约束了引力耦合标量场的存在？
• RQ2 在GW150914观测波形的约束下，可变牛顿常数或修正色散关系的模型表现如何？
• RQ3 GW150914对引力向大额外维度泄漏或引力传播速度偏离施加了何种限制？
• RQ4 与Kerr黑洞相比，奇异致密天体模型（如玻色子星或引力星）在多大程度上能重现观测到的GW150914信号？
• RQ5 若检测到GW150914的电磁对应体，将对引力传播速度与洛伦兹不变性施加何种额外约束？

主要发现

• GW150914为迄今最强的直接约束，针对强场引力波传播与广义相对论偏离。
• 信号中未观测到异常，排除了显著标量场激发或引力向大额外维度泄漏的可能性。
• 观测结果将牛顿常数的可变性与引力传播速度约束在与广义相对论一致的水平。
• GW150914对修正色散关系与引力洛伦兹破坏施加了强约束，尤其在结合潜在电磁对应体时更为显著。
• 无法重现观测到的铃荡与并合动力学的奇异致密天体模型已被数据排除。
• 该事件凸显了在修正引力理论中建立更完整理论框架的迫切需求，以准确模拟双黑洞并合过程。