薄吸积盘照射下中子星的偏振图像：与黑洞的对比
Polarization Images of Neutron Stars Illuminated by a Thin Accretion Disk: A Comparison with Black Holes
AI总结：
该研究构建了多方物态方程的静态球对称中子星模型，求解相关方程得到其线偏振图像，通过与史瓦西黑洞对比，发现二者偏振图像存在差异，可用于区分两类致密天体。
AI中文摘要：
我们研究由几何薄且光学薄的吸积盘照射的静态、球对称中子星的线偏振图像。中子星的平衡构型由多方物态方程构建，在几何光学近似下求解零测地线方程和线偏振矢量的平行输运方程。数值结果表明，总偏振强度通常与总强度正相关，在中子星表面附近达到最大值；随着观测者倾角增大，偏振图像的对称性逐渐被破坏。此外，磁场构型主要影响偏振矢量的方向，对整体偏振强度分布的影响相对有限。为进一步表征偏振方向的空间结构，我们引入净电矢量位置角χ_net和二阶方位角傅里叶模∠β₂。与史瓦西黑洞的偏振图像对比显示，两类致密天体在强偏振区域的位置及无偏振信号的中心区域大小上存在明显差异。这些结果表明，线偏振图像提供了超出总强度图像的信息，可用于区分中子星与黑洞。
英文摘要：
We investigate linear polarization images of static, spherically symmetric neutron stars illuminated by a geometrically and optically thin accretion disk. Neutron star equilibrium configurations are constructed with a polytropic equation of state, and the null geodesic equations and the parallel transport equation for the linear polarization vector are solved in the geometric optics approximation. The numerical results show that the total polarized intensity is generally positively correlated with the total intensity and reaches its maximum near the neutron star surface. As the observer inclination increases, the symmetry of the polarization images is progressively broken. In addition, the magnetic field configuration mainly affects the direction of the polarization vectors, while its influence on the overall polarized intensity distribution is comparatively limited. To further characterize the spatial structure of the polarization direction, we introduce the net electric vector position angle $χ_{\mathrm{net}}$ and the second azimuthal Fourier mode $\angleβ_2$. A comparison with polarization images of a Schwarzschild black hole reveals clear differences between the two types of compact objects in the locations of strongly polarized regions and the size of the central region without a polarization signal. These results show that linear polarization images provide information beyond total intensity images for distinguishing neutron stars from black holes.
