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宇宙射线和星系的风

伴随的附图示出了在软X射线的内乳白色方式。它是指示热气体,可能是由超新星加热的 - 星形成率,因此,超新星率,是在内部星系非常高。超新星是已知的加速宇宙射线,所以宇宙射线也必须存在。我们做了从由气体压力和宇宙射线压力驱动的内星系的风力的模型,在大致相等的量(Everett等人,2008年,2010年),其能够以适合观测。

How does cosmic ray pressure actually drive thermal gas? This is a bit subtle. Cosmic rays, after all, are relativistic particles. They should just be able to stream out of the galaxy at the speed of light. However, it turns out that  a large flux of cosmic rays streaming through a magnetized plasma leads to the growth of magnetic fluctuations. These fluctuations extract momentum and energy from the cosmic rays, and transfer it to the gas. The end result is that the cosmic rays and thermal gas are strongly coupled together. This works very nicely in hot, fully ionized gas. It doesn't work well at all, however, in cool interstellar clouds (Everett & Zweibel 2011), because the fluctuations are rapidly dissipated in cold gas. This means that the cooler gas seen in outflows from other galaxies must be driven by another mechanism, or must have formed once the wind had already been accelerated.

我们正在申请类似的想法与其他星系,那里的条件可以说是相当不同的。 M82,其中,宇宙射线密度,气体密度,和磁场强都很高的星暴,是一个很好的例子。在这里,风可能是蒸发流。

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