General relativistic study of astrophysical jets with internal shocks
General relativistic study of astrophysical jets with internal shocks
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具有内激波的天体物理喷流的广义相对论研究
DOI：
10.1093/mnras/stx967
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发表时间：
2017
影响因子：
4.8
通讯作者：
I. Chattopadhyay
中科院分区：
文献类型：
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作者：
Mukesh K. Vyas;I. Chattopadhyay
我们探索了在黑洞周围的喷流中形成稳定内激波的可能性。我们考虑由相对论状态方程描述的流体，以Schwarzschild度规绕对称轴($\theta=0$)流动。我们使用两种喷流几何模型，(I)圆锥形几何和(Ii)非圆锥形截面几何。具有锥形几何形状的射流是一种光滑的流动。而具有非圆锥截面的射流则经历多个声速点甚至立定激波。当激波位置离中心黑洞较远时，喷流激波变得更强。能量很高和能量很低的喷流不会产生激波，但中等能量的喷流会产生激波。与外部介质诱导的激波相比，这些激波的一个优点是，这些激波对喷嘴的末端速度没有影响，但可能是粒子加速的场所。通常，对于任何几何形状的喷流，能量为1.8~c^2$的喷流将达到$v_\inty=0.813c$的终速。而对于吸积盘内环长度尺度为40美元的非圆锥截面射流，则在吸积盘压缩比为2.7美元、吸积盘内环长度尺度为7.5美元时，会形成稳定激波。此外，电子-质子喷流似乎蕴藏着最强的冲击波。我们讨论了这种情况可能产生的后果。
We explore the possibility of formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry ($\theta=0$) in a Schwarzschild metric. We use two models for the jet geometry, (i) a conical geometry and (ii) a geometry with non-conical cross-section. Jet with conical geometry is smooth flow. While the jet with non-conical cross section undergoes multiple sonic point and even standing shock. The jet shock becomes stronger, as the shock location is situated further from the central black hole. Jets with very high energy and very low energy do not harbour shocks, but jets with intermediate energies do harbour shocks. One advantage of these shocks, as opposed to shocks mediated by external medium is that, these shocks have no effect on the jet terminal speed, but may act as possible sites for particle acceleration. Typically, a jet with energy $1.8~c^2$, will achieve a terminal speed of $v_\infty=0.813c$ for jet with any geometry. But for a jet of non-conical cross-section for which the length scale of the inner torus of the accretion disc is $40\rg$, then in addition, a steady shock will form at $\rsh \sim 7.5\rg$ and compression ratio of $R\sim 2.7$. Moreover, electron-proton jet seems to harbour the strongest shock. We discuss possible consequences of such a scenario.