论文标题
宇宙射线注射对银河盘中磁通管的影响
The Impact of Cosmic Ray Injection on Magnetic Flux Tubes in a Galactic Disk
论文作者
论文摘要
在银河系磁盘中，当非热压支持超过一定阈值时，帕克不稳定会导致。帕克不稳定性中考虑的非热压是宇宙射线压力和磁压。这种不稳定需要很长时间才能饱和$（> 500 \，\ mathrm {myr}）$，并假定具有固定宇宙射线压力与气体压力比的背景。实际上，将银河宇宙射线注入局部区域$（<100 \，\ mathrm {pc}）$，例如超新星等事件，从而增加了宇宙射线压力与气压比。在这项工作中，我们使用\ texttt {achena ++}代码在宇宙射线磁磁性模拟中检查了这种宇宙射线注入对大尺度$（\ sim 1 \，\ mathrm {kpc}）$的影响。我们改变了背景特性，主流宇宙射线传输机制和模拟运行之间的注射特性。我们发现，注射会破坏较短的时间尺度上的星际介质，而不是帕克不稳定。如果宇宙射线通过对流传输是主导的，则宇宙射线注入会在短时间尺度上破坏磁盘$（<100 \，\ mathrm {myr}）$。如果流媒体不稳定性的宇宙射线传输是主导的，则注入会在初始注入$（> 150 \，\ mathrm {myr}）$之后很长时间创建一个浮力的通量管。最后，当宇宙射线通过扩散占主导地位时，注射的宇宙射线使整个磁通管在短时间内压力$（\ sim 10 \，\ mathrm {myr}）$。这种过压的压力将气体从管子上推开，并在时间尺度上驱动浮力上升，类似于对流式的情况。
In galactic disks, the Parker instability results when non-thermal pressure support exceeds a certain threshold. The non-thermal pressures considered in the Parker instability are cosmic ray pressure and magnetic pressure. This instability takes a long time to saturate $(>500 \, \mathrm{Myr})$ and assumes a background with fixed cosmic ray pressure to gas pressure ratio. In reality, galactic cosmic rays are injected into localized regions $(< 100 \,\mathrm{pc})$ by events like supernovae, increasing the cosmic ray pressure to gas pressure ratio. In this work, we examine the effect of such cosmic ray injection on large scales $ (\sim 1\,\mathrm{kpc})$ in cosmic ray magnetohydrodynamic simulations using the \texttt{Athena++} code. We vary the background properties, dominant cosmic ray transport mechanism, and injection characteristics between our simulation runs. We find the injection will disrupt the interstellar medium on shorter timescales than the Parker instability. If cosmic ray transport by advection is dominant, cosmic ray injection disrupts the disk on short time scales $(<100\,\mathrm{Myr})$. If cosmic ray transport by the streaming instability is dominant, the injection creates a buoyant flux tube long after the initial injection $(>150\,\mathrm{Myr})$. Finally, when cosmic ray transport by diffusion dominates, the injected cosmic rays make an entire flux tube over pressured in a short time $(\sim 10 \, \mathrm{Myr})$. This over pressure pushes gas off the tube and drives buoyant rise on time scales similar to the advection dominated case.
