标题： 超大质量黑洞周围非热电子的偏振翻转观测调查 显示英文标题

标题： Survey of Non-thermal Electron around Supermassive Black Holes through Polarization Flips

摘要： 光学厚度较大的非热同步辐射源显著地使线性偏振矢量与观测屏上的投影磁场线平行，尽管在众所周知的光学薄情况下它们是垂直的。 为了阐明矢量和场之间的复杂关系，并通过图像研究非热电子的能量和空间分布，我们在亚毫米波长下进行了偏振辐射传递计算。 这里的计算基于半解析的准力自由喷流模型，其中含有能量呈幂律分布的非热电子。 在计算出的图像中，我们发现在靠近黑洞的反向（远离）喷流基部存在一个线性偏振（LP）矢量的$90^\circ$翻转现象，这是由于同步自吸收效应的大光学深度引起的。 在高频率下的光子环上也观察到了 LP 矢量的$90^\circ$翻转现象，这是因为光线处的光学深度较大，这归因于光偏折效应。 此外，我们在反向喷流和光子环上看到了圆偏振（CP）分量符号的翻转。 此外，我们表明这些偏振翻转现象与谱指数图中的大值合成在一起，并且在法拉第旋转度（RM）图中也会产生突出特征。 由于翻转条件取决于磁场强度和配置以及电子的能量分布，我们可以预期这些偏振翻转现象将为我们提供黑洞周围存在非热电子的观测证据，并为等离子体喷流的磁驱动机制提供线索。 显示英文摘要

摘要： Optically thick non-thermal synchrotron sources notably produce linear polarization vectors being parallel to projected magnetic field lines on the observer's screen, although they are perpendicular in well-known optically thin cases. To elucidate the complex relationship between the vectors and fields and to investigate the energy and spatial distribution of non-thermal electrons through the images, we perform polarization radiative transfer calculations at submillimeter wavelengths. Here the calculations are based on semi-analytic force-free jet models with non-thermal electrons with a power-law energy distribution. In calculated images, we find a $90^\circ$-flip of linear polarization (LP) vectors at the base of counter-side (receding) jet near a black hole, which occurs because of large optical depths for synchrotron self-absorption effect. The $90^\circ$-flip of LP vectors is also seen on the photon ring at a high frequency, since the optical depth along the rays is large there due to the light bending effect. In addition, we see the flip of the sign of circular polarization (CP) components on the counter jet and photon ring. Furthermore, we show that these polarization flips are synthesized with large values in the spectral index map, and also give rise to outstanding features in the Faraday Rotation Measure (RM) map. Since the conditions of flipping depend on the magnetic field strength and configuration and the energy distribution of electrons, we can expect that the polarization flips will provide us with an observational evidence for the presence of non-thermal electrons around the black hole, and a clue to the magnetically driving mechanism of plasma jets.