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Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field
Publications of the Astronomical Society of Australia ( IF 4.5 ) Pub Date : 2020-06-11 , DOI: 10.1017/pasa.2020.14
S. M. Ghoreyshi

The observations and simulations have revealed that large-scale magnetic field and outflows can exist in the inner regions of an advection-dominated accretion disc where the resistive diffusion may also be important. In the present paper, the roles of large-scale magnetic field and outflows in the structure of resistive advection-dominated accretion discs are explored by assuming that the accretion flow is radially self-similar. In the non-ideal magnetohydrodynamic (MHD) approximation, the results show that the angular velocity is always sub-Keplerian when both the outflow and the large-scale magnetic field are taken into account. A stronger toroidal field component leads to faster rotation, while the disc rotates with faster rate if the vertical field component is weaker. The increase of magnetic diffusivity causes the infall velocity to be close to Keplerian velocity. Although the previous studies in the ideal MHD approximation have shown that the disc temperature decreases due to the vertical field component, we find that the effect of vertical field component on the temperature of a resistive disc depends on the magnetic diffusivity. When the magnetic diffusivity is high, the more efficient mechanism for decreasing the disc temperature can be the outflows, and not the large-scale magnetic field. In such a limit of the magnetic diffusivity, the components of the large-scale magnetic field enhance the gas temperature. The increase of temperature can lead to heating and acceleration of the electrons and help us to explain the origin of phenomena such as the flares in Sgr A*. On the other hand, the infall velocity in such a limit rises as the temperature increases, and therefore the surface density falls to too low values. Any change in the density profile can alter the structure and the emitted spectrum of disc.

中文翻译:

具有外流和大范围磁场的电阻式ADAF的自相似结构

观察和模拟表明,在以平流为主的吸积盘内部区域可能存在大规模磁场和外流,其中电阻扩散也可能很重要。在本文中,假设吸积流是径向自相似的,探讨了大尺度磁场和外流在阻力平流主导吸积盘结构中的作用。在非理想磁流体动力学(MHD)近似中,结果表明,当同时考虑流出和大尺度磁场时,角速度总是亚开普勒。更强的环形场分量导致更快的旋转,而如果垂直场分量较弱,则圆盘以更快的速度旋转。磁扩散率的增加导致下落速度接近开普勒速度。尽管先前对理想 MHD 近似的研究表明,由于垂直场分量,圆盘温度会降低,但我们发现垂直场分量对电阻盘温度的影响取决于磁扩散率。当磁扩散率高时,降低圆盘温度的更有效机制可能是流出物,而不是大规模磁场。在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 尽管先前对理想 MHD 近似的研究表明,由于垂直场分量,圆盘温度会降低,但我们发现垂直场分量对电阻盘温度的影响取决于磁扩散率。当磁扩散率高时,降低圆盘温度的更有效机制可能是流出物,而不是大规模磁场。在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 尽管先前对理想 MHD 近似的研究表明,由于垂直场分量,圆盘温度会降低,但我们发现垂直场分量对电阻盘温度的影响取决于磁扩散率。当磁扩散率高时,降低圆盘温度的更有效机制可能是流出物,而不是大规模磁场。在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 我们发现垂直场分量对电阻盘温度的影响取决于磁扩散率。当磁扩散率高时,降低圆盘温度的更有效机制可能是流出物,而不是大规模磁场。在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 我们发现垂直场分量对电阻盘温度的影响取决于磁扩散率。当磁扩散率高时,降低圆盘温度的更有效机制可能是流出物,而不是大规模磁场。在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源 在这样的磁扩散率极限下,大尺度磁场的成分提高了气体温度。温度的升高会导致电子加热和加速,帮助我们解释人马座耀斑等现象的起源*. 另一方面,在这种极限下的下落速度随着温度的升高而升高,因此表面密度下降到太低的值。密度分布的任何变化都会改变圆盘的结构和发射光谱。
更新日期:2020-06-11
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