标题： M87喷流在约十个史瓦西半径尺度上的相对论电子和磁场 显示英文标题

标题： Relativistic electrons and magnetic field of the M87 jet on ~ten Schwarzschild radii scale

摘要： 我们研究M87喷流中磁场和相对论电子的能量密度。由于喷流基部的射电核心与同步自吸收（SSA）的光学厚表面相同，观测频率与SSA转折频率相同。作为第一步，我们假设射电核心为简单的均匀球形几何结构。利用在43 GHz下由甚长基线阵列测量的射电核心的角尺寸，我们根据标准SSA公式估计磁场的能量密度（$U_{B}$）和相对论电子的能量密度（$U_{e}$）。施加Poynting功率和相对论电子功率应小于喷流总功率的条件，我们发现（i）磁场强度（$B_{tot}$）的允许范围是从1 G到15 G，且（ii）$1 times 10^{-5} < U_{e}/U_{B} < 6 times 10^{2}$成立。$U_{e}/U_{B}$的不确定性来自于射电核心的角尺寸和核心中非热电子的最小洛伦兹因子（$gamma_{e,min}$）的强依赖性。在约10个史瓦西半径尺度上，结果能量学是与磁流体动力学喷流一致还是与动能主导喷流一致仍然是开放问题。 显示英文摘要

摘要： We explore energy densities of magnetic field and relativistic electrons in the M87 jet. Since the radio core at the jet base is identical to the optically thick surface against synchrotron self absorption (SSA), the observing frequency is identical to the SSA turnover frequency. As a first step, we assume the radio core as a simple uniform sphere geometry. Using the observed angular size of the radio core measured by the Very Long Baseline Array at 43 GHz, we estimate the energy densities of magnetic field ($U_{B}$) and relativistic electrons ($U_{e}$) based on the standard SSA formula. Imposing the condition that the Poynting power and relativistic electron one should be smaller than the total power of the jet, we find that (i) the allowed range of the magnetic field strength ($B_{tot}$) is from 1 G to 15 G, and that (ii) $1 times 10^{-5} < U_{e}/U_{B} < 6 times 10^{2}$ holds. The uncertainty of $U_{e}/U_{B}$ comes from the strong dependence on the angular size of the radio core and the minimum Lorentz factor of non-thermal electrons ($gamma_{e,min}$) in the core. It is still open that the resultant energetics is consistent with either the magnetohydrodynamic jet or with kinetic power dominated jet even on ~10 Schwarzschild radii scale.