Neutron stars are compact and dense celestial objects that offer the unique opportunity to explore matter and its interactions under conditions that cannot be reproduced elsewhere in the Universe. Their extreme gravitational, rotational and magnetic energy reservoirs fuel the large variety of their emission, which encompasses all available multi-messenger tracers: electromagnetic and gravitational waves, neutrinos, and cosmic rays. However, accurately measuring global neutron-star properties such as mass, radius, and moment of inertia poses significant challenges. Probing internal characteristics such as the crustal composition or superfluid physics is even more complex. This article provides a comprehensive review of the different methods employed to measure neutron-star characteristics and the level of reliance on theoretical models. Understanding these measurement techniques is crucial for advancing our knowledge of neutron-star physics. We also highlight the importance of employing independent methods and adopting a multi-messenger approach to gather complementary data from various observable phenomena as exemplified by the recent breakthroughs in gravitational-wave astronomy and the landmark detection of a binary neutron-star merger. Consolidating the current state of knowledge on neutron-star measurements will enable an accurate interpretation of the current data and errors, and better planning for future observations and experiments.

中文翻译：

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多信使时代的中子星测量

中子星是致密而致密的天体，为在宇宙其他地方无法重现的条件下探索物质及其相互作用提供了独特的机会。它们的极端引力、旋转和磁能库为它们的多种发射提供了燃料，其中包括所有可用的多信使示踪剂：电磁波和引力波、中微子和宇宙射线。然而，准确测量质量、半径和转动惯量等全球中子星特性提出了重大挑战。探测地壳成分或超流体物理学等内部特征甚至更加复杂。本文全面回顾了用于测量中子星特征的不同方法以及对理论模型的依赖程度。了解这些测量技术对于增进我们对中子星物理学的了解至关重要。我们还强调了采用独立方法和采用多信使方法从各种可观测现象中收集补充数据的重要性，例如引力波天文学的最新突破和双中子星合并的里程碑式探测。巩固当前中子星测量知识将能够准确解释当前数据和误差，并更好地规划未来的观测和实验。