[论文解读] Probing Fundamental Physics with Gravitational Waves

Zack Carson|arXiv (Cornell University)|May 10, 2020

Pulsars and Gravitational Waves Research参考文献 481被引用 3

一句话总结

本论文研究了双黑洞与双中子星并合产生的引力波如何探测基础物理，重点通过潮汐可变形性探究核物质性质，并通过波形一致性与超越Kerr度规检验广义相对论。论文推导出对中子星方程态的新约束，并提出一种参数化度规以检验偏离Kerr黑洞的行为，为未来多波段与多信使观测提供测试基础。

ABSTRACT

The explosive coalescence of two black holes 1.3 billion light years away has for the very first time allowed us to peer into the extreme gravity region of spacetime surrounding these events. With these maximally compact objects reaching speeds up to 60% the speed of light, collision events such as these create harsh spacetime environments where the fields are strong, non-linear, and highly dynamical -- a place yet un-probed in human history. On September 14, 2015, the iconic chirp signal from such an event was registered simultaneously by both of the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors -- by an unparalleled feat of modern engineering. Dubbed "GW150914", this gravitational wave event paved the way for an entirely new observing window into the universe, providing for the unique opportunity to probe fundamental physics from an entirely new viewpoint. Since this historic event, the LIGO/Virgo collaboration (LVC) has further identified ten additional gravitational wave signals in its first two observing runs, composed of a myriad of different events. Important among these new cataloged detections is GW170817, the first detection of gravitational waves from the merger of two neutron stars, giving way to new insight into the supranuclear physics resident within. This thesis explores this new unique opportunity to harness the information encoded within gravitational waves in regards to their source whence they came, to probe fundamental physics from an entirely new perspective. Part A focuses on probing nuclear physics by way of the tidal information encoded within gravitational waves from binary neutron star mergers. Part B focuses on testing general relativity from such events by way of the remnants of such spacetime encoded within the gravitational wave signal.

研究动机与目标

• 利用双中子星并合引力波中编码的潮汐信息，约束核物质方程态。
• 通过引入GW170817的约束，改进中子星可观测量之间普遍关系的估计。
• 通过引力波信号旋近与 ringing 下降阶段的一致性检验，在强场引力中检验广义相对论。
• 开发一种新的参数化超越Kerr度规，以建模偏离Kerr黑洞的行为并预测可观测效应。
• 通过空间基与地面探测器之间的多波段探测，实现未来对引力理论的检验。

提出的方法

• 分析双中子星并合产生的引力波信号，提取潮汐可变形性参数。
• 利用贝叶斯推断将潮汐可变形性与对称能及其斜率等核物质参数关联。
• 应用中子星质量、半径与潮汐可变形性之间的普遍关系，改进参数估计。
• 通过比较后牛顿波形与ringdown模态，执行广义相对论的参数化检验。
• 构建一种超越Kerr解的通用时空度规，引入自由参数以描述非Kerr黑洞候选体。
• 模拟超越Kerr度规的可观测效应，如光子环与阴影特征的偏移，为未来事件视界望远镜观测提供预测。

实验结果

研究问题

• RQ1 如何利用GW170817及未来探测中的潮汐信息，对核物质方程态施加约束？
• RQ2 如何通过改进中子星可观测量之间的普遍关系，提升引力波天文学中的参数估计精度？
• RQ3 双黑洞并合引力波信号的旋近与ringing下降阶段在多大程度上与广义相对论预测一致？
• RQ4 当以参数化方式偏离Kerr度规时，黑洞时空结构中会产生哪些可观测特征？
• RQ5 未来空间基与地面探测器之间的多波段引力波探测，如何提升对广义相对论之外引力理论的检验能力？

主要发现

• GW170817的潮汐可变形性测量为致密核物质中对称能及其斜率提供了新约束。
• 推导出中子星质量、半径与潮汐可变形性之间改进的普遍关系，降低了未来观测中参数估计的退化程度。
• 旋近与ringing下降阶段的一致性检验对替代引力理论（包括标量-张量与陈-西蒙斯引力）施加了强约束。
• 参数化超越Kerr度规预测了光子环与阴影形态的可测量偏离，未来可通过事件视界望远镜探测。
• 多事件叠加与空间基与地面探测器之间的多波段观测显著提升了对偏离广义相对论行为的敏感度。
• 该框架使利用未来探测器的引力波数据对黑洞唯一性与无毛定理进行定量检验成为可能。