[论文解读] Tests of Classical Gravity with Radio Pulsars

Zexin Hu, Xueli Miao+1 more|arXiv (Cornell University)|Mar 30, 2023

Pulsars and Gravitational Waves Research参考文献 129被引用 8

一句话总结

这篇论文以教育性的方式回顾脉冲星定时作为在准静态强场引力中测试广义相对论的工具，涉及 Hulse-Taylor、双星与三重脉冲星，并讨论中子星结构与修正引力约束。

ABSTRACT

Tests of gravity are important to the development of our understanding of gravitation and spacetime. Binary pulsars provide a superb playground for testing gravity theories. In this chapter we pedagogically review the basics behind pulsar observations and pulsar timing. We illustrate various recent strong-field tests of the general relativity (GR) from the Hulse-Taylor pulsar PSR B1913+16, the double pulsar PSR J0737$-$3039, and the triple pulsar PSR J0337+1715. We also overview the inner structure of neutron stars (NSs) that may influence some gravity tests, and have used the scalar-tensor gravity and massive gravity theories as examples to demonstrate the usefulness of pulsar timing in constraining specific modified gravity theories. Outlooks to new radio telescopes for pulsar timing and synergies with other strong-field gravity tests are also presented.

研究动机与目标

• Explain pulsar timing basics and how TOAs are modeled in a Solar System Barycentre frame.
• Describe the Damour-Deruelle parametrized post-Keplerian (DD-PPK) formalism for binary pulsars.
• Show how GR-specific PPK parameters constrain neutron star masses and test gravity in strong fields.
• Present how neutron star inner structure and spin effects influence gravity tests using scalar-tensor and massive gravity examples.
• Outline future prospects with new radio telescopes and synergies with other strong-field gravity tests.

提出的方法

• Introduce pulsar timing and dispersion effects in the ISM and describe TOA formation.
• Present the DD timing model and the PPK parameters used to describe relativistic orbital effects.
• Provide GR expressions for PPK parameters and discuss degeneracies and alternative parametrizations (e.g., h3, h4).
• Explain geodetic and orbital precession and their potential to probe neutron star moments of inertia and equation of state.
• Illustrate self-consistency checks in GR via mass-mass diagrams using measured PPK parameters.
• Discuss how timing data from well-studied systems test gravity theories and constrain modified gravity models.

Figure 1: The period–period derivative diagram for pulsars Manchester:2005 . The black dots are pulsars with pulsed emission in the radio band and the red circles mark binary systems. We also denote “AXP” for systems that are anomalous X-ray pulsars or soft $\gamma$ -ray repeaters, “RRAT” for system

实验结果

研究问题

• RQ1 GR在准静态强场条件下描述脉冲星双星动力学的准确性如何？
• RQ2 脉冲星定时能否以足够高的精度测量 PPK 参数来测试 GR 并约束 NS 属性？
• RQ3 自旋-轨道耦合与地测预cession 对引力测试和 NS EOS 有何含义？
• RQ4 替代引力理论如何在脉冲星定时观测中表现并能得到何种约束？

主要发现

• 对所测试的脉冲星系统，GR 的预测与观测在报告的不确定性范围内一致。
• 对于 PSR B1913+16，在经过 Shklovskii 和银河系修正后，固有轨道衰减率与 GR 一致，误差在 10^3 的几个数量级内。
• 对于 PSR J0737−3039A/B，多个独立测试（dot omega、gamma、dotP_b 和 Shapiro 参数）与 GR 一致，误差在 10^3 的几个数量级内。
• 质量-质量图显示在不确定性范围内的 PPK 曲线相交，支持在强场条件下的 GR。
• 地测进动在一些系统中被探测到，能够测试自旋-轨道耦合及潜在的 NS EOS 含义。
• 定时框架通过 PPK 参数的参数偏差，允许对修正引力理论进行探索。

Figure 2: Stack of 100 single pulses from PSR J2222 $-$ 0137, observed with the FAST telescope Miao:2023gkr . The line in the top is the integrated profile of these 100 pulses.