云对富气矮星系动力学和化学演化的影响
The effect of clouds on the dynamical and chemical evolution of gas-rich dwarf galaxies
摘要：
我们研究了云对富气矮星系动力学和化学演化的影响，特别关注两个类似于IZw 18和NGC 1569的模型星系。我们考虑这两种情况，云放在模拟的开始，并不断创建下落的。由于动力学过程和热蒸发，云只存活了几十万年，但在这段时间里，它们充当了额外的冷却剂，与没有云的模型相比，多云模型的内能通常减少了20 - 40%。这些云延缓了大规模外流的发展，因此有助于在星系内保留更大量的气体。然而，特别是在不断产生下落云的模型中，它们的子弹效应可以刺穿膨胀的超级壳，并产生洞，超级气泡可以通过这些洞排出新鲜产生的金属。此外，假设云的化学成分是原始的，它们与超级气泡的相互作用稀释了气体，相对于扩散模型所获得的金属丰度降低了约0.4 dex。
英文摘要：
We study the effects of clouds on the dynamical and chemical evolution of gas-rich dwarf galaxies, in particular focusing on two model galaxies similar to IZw18 and NGC1569. We consider both scenarios, clouds put at the beginning of the simulation and continuously created infalling ones. Due to dynamical processes and thermal evaporation, the clouds survive only a few tens of Myr, but during this time they act as an additional cooling agent and the internal energy of cloudy models is typically reduced by 20 - 40% in comparison with models without clouds. The clouds delay the development of large-scale outflows, therefore helping to retain a larger amount of gas inside the galaxy. However, especially in models with continuous creation of infalling clouds, their bullet effect can pierce the expanding supershell and create holes through which the superbubble can vent freshly produced metals. Moreover, assuming a pristine chemical composition for the clouds, their interaction with the superbubble dilutes the gas, reducing the metallicity (by up to ~ 0.4 dex) with respect to the one attained by diffuse models.
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