标题： 密度依赖的声速及其在中子星中的后果 显示英文标题

标题： Density dependent speed of sound and its consequences in neutron stars

摘要： 我们引入了一个参数化的密度依赖声速，并构建了中子星的状态方程集合，这些状态方程被发现与使用相对论平均场理论计算的真实状态方程非常相似。 我们表明，这些参数中的每一个都表现出与致密星体性质相关的独特特征。 质量-半径图中特殊点的出现是中子星的一个重要结果，这在混合星的情况下更为常见。 我们还表明，在这些强子状态方程中，声速的曲率项会改变符号，而无需物质达到共形极限或经历任何相变。 这与每个核子的能量的一阶导数达到最大值有关。 我们还检查了RMF模型以及密度依赖参数化声速的迹异常和多态指数的详细行为。 我们的分析表明，在高密度下，迹异常的符号对EOS的刚度或柔软度敏感。 来自质量-半径和潮汐变形的不同的观测约束可以限制所提出声速模型中的参数范围。 显示英文摘要

摘要： We introduce a parametrized density-dependent speed of sound and construct an ensemble of equations of state for neutron stars which are found to closely resemble the realistic equations of state calculated using relativistic mean field theory. We show that each of these parameters display an unique feature relevant to the properties of the compact stars. The emergence of special points in the Mass-Radius plot is a significant outcome for neutron stars which is more commonly seen in case of hybrid stars. We have also shown that the curvature term in the speed of sound changes its sign for these hadronic equations of state without the matter reaching the conformal limit or undergoing any phase transition. It is related to the 1st derivative of the energy per nucleon reaching a maximum. We have also examined the detailed behavior of the trace anomaly and polytropic index for RMF models, as well as for a density-dependent parametrized speed of sound. Our analysis demonstrates that the sign of the trace anomaly at high densities is sensitive to the stiffness or softness of the EOS. Different observational constraints from mass-radius and tidal deformability can restrict the range of parameters in the proposed speed of sound model.