Matter Density Distribution of General Relativistic Highly Magnetized Jets Driven by Black Holes
Matter Density Distribution of General Relativistic Highly Magnetized Jets Driven by Black Holes
复制标题
DOI：
10.3847/1538-4357/abe61b
复制
发表时间：
2021-02
期刊：
影响因子：
--
通讯作者：
Taiki Ogihara;Takumi Ogawa;K. Toma
中科院分区：
文献类型：
--
作者：
Taiki Ogihara;Takumi Ogawa;K. Toma
高分辨率甚长基线干涉（VLBI）射电观测已经解决了活动星系核喷流的详细发射结构。广义相对论磁流体力学（GRMHD）模拟提高了对射流产生物理的理解，尽管理论研究仍然难以限制射流物质的起源和分布。我们建立了一个新的稳定轴对称GRMHD射流模型，以获得黑洞磁球的近似解，并研究了射流的物质密度分布。通过假设固定的极向磁场形状，模拟无力解析解和GRMHD模拟结果，并假设分离表面的极向速度恒定，划分流入和外流，数值求解了分离表面磁场线之间的力平衡，解析求解了物质速度和密度沿磁场线的分布。我们发现在抛物线场模型中，分离面密度大致与离黑洞远的区域一致，其中rs为分离面半径。当BH自旋较大或分离面处的速度较小时，分离面处的密度更靠近射流边缘集中。我们的半解析模型，结合辐射传递计算，可以帮助我们解释高分辨率VLBI观测并了解喷射物质的起源。
High-resolution very long baseline interferometry (VLBI) radio observations have resolved the detailed emission structures of active galactic nucleus jets. General relativistic magnetohydrodynamic (GRMHD) simulations have improved the understanding of jet production physics, although theoretical studies still have difficulty constraining the origin and distribution of jetted matter. We construct a new steady, axisymmetric GRMHD jet model to obtain approximate solutions of black hole (BH) magnetospheres, and examine the matter density distribution of jets. By assuming fixed poloidal magnetic field shapes that mimic force-free analytic solutions and GRMHD simulation results and assuming constant poloidal velocity at the separation surface, which divides the inflow and outflow, we numerically solve the force balance between the field lines at the separation surface and analytically solve the distributions of matter velocity and density along the field lines. We find that the densities at the separation surface in our parabolic field models roughly follow in the far zone from the BH, where r ss is the radius of the separation surface. When the BH spin is larger or the velocity at the separation surface is smaller, the density at the separation surface becomes concentrated closer to the jet edge. Our semianalytic model, combined with radiative transfer calculations, may help us interpret the high-resolution VLBI observations and understand the origin of jetted matter.