AI 中文总结
研究冷中子星物质声速密度依赖性，通过简化参数化方法结合模拟确定其与合并结果的相关性，发现声速导数与合并后引力波频率峰值有近似关系，揭示多信使观测对高密度物质行为敏感及解析高密度物理的困难。
AI 中文摘要
冷中子星物质中声速的密度依赖性仍受限制，这对确定高密度状态方程至关重要。虽然双中子星合并模拟纳入了微观物理学，但中子星核心声速对可观测特征的直接影响未被系统探索。我们引入简化参数化方法，通过重子化学势导数控制超核密度下声速变化。利用WhiskyTHC代码进行模拟，确定声速斜率参数与合并结果的相关性。结果表明多信使观测对中子星核心最高密度物质行为敏感。进一步分析发现声速导数与合并后引力波频率峰值存在近似与状态方程无关的关系，这虽不绝对普遍，但表明合并后引力波保留了高密度状态方程的可测信息，同时也凸显了解析潜在高密度物理的困难及发展参数化框架的必要性。
英文摘要
The density dependence of the speed of sound in cold neutron star matter remains poorly constrained and is central to determining the high-density equation of state (EOS). While binary neutron star (BNS) merger simulations increasingly incorporate detailed microphysics, the direct impact of the sound-speed in the neutron star core on observable signatures has not been systematically explored. We address this by introducing a simplified parametrization that suppresses microphysics while allowing controlled variation of the sound speed at supranuclear densities through its derivative with respect to the baryon chemical potential. Using the WhiskyTHC code, we perform a suite of fully relativistic BNS merger simulations and identify correlations between the sound-speed slope parameter and key merger outcomes, including remnant properties and post-merger GW frequencies. These results demonstrate that multimessenger observables are sensitive to the behavior of matter at the highest densities reached in neutron star cores. We further analyze gravitational-wave signals from the CoRe database of binary neutron star merger simulations employing more realistic equations of state. Our analysis reveals approximately EOS-independent relations between the derivative of the sound speed and the peak post-merger gravitational-wave frequency. Although these relations cannot be considered truly quasi-universal, they nonetheless indicate that post-merger gravitational waves retain measurable information about the EOS at he highest densities. At the same time, the remaining EOS dependence highlights the difficulty of isolating the underlying high-density physics and motivates the development of targeted parameterized frameworks for interpreting future multimessenger observations.
Comments31 pages, 11 figures. Fixed an outdated figure caption in figure 11, Fixed typos in the text and references
