论文标题

关于失控星对矮星系的影响以及已解决的星际介质的影响

On the impact of runaway stars on dwarf galaxies with resolved interstellar medium

论文作者

Steinwandel, Ulrich P., Bryan, Greg L., Somerville, Rachel S., Hayward, Christopher C., Burkhart, Blakesley

论文摘要

大约有10%至20%的大型恒星可能会被踢出其出生簇,然后爆炸为超新星。这些“失控的恒星”可能在驱动银河流出并用金属富集卷乳介质中起着至关重要的作用。为了研究这种效果,我们进行了高分辨率矮星系模拟,其中包括速度踢到超过8 m $ $ _ {\ odot} $以上的大量O/B星。我们考虑两种情况,一种采用电源法速度分布来踢球速度,导致更多具有较高速度踢的恒星,以及更温和的情况,并具有麦克斯韦时速分布。我们明确解析了多相星际介质(ISM),并包括非平衡冷却和化学通道。我们采用解决的反馈方案(\ textsc {griffin}),在该方案中我们从IMF中进行了单个大型恒星。我们遵循这些恒星的寿命,并在周围的气体中添加他们的光电离辐射,其紫外线辐射场和光电加热速率。在他们一生结束时,我们将大量人口爆炸为核心崩溃超新星(CCSN)。在模拟巨大恒星的模拟中,我们添加了额外的(出生)速度踢,这些速度模仿了两个身体相互作用,这些相互作用无法在我们的模拟中完全解析。我们发现,包含失控或走路恒星场景对质量,金属,动量和能量流出以及相应的负载因子有影响。我们发现质量,金属和动量载荷增加了2-3倍,而在失控的情况下,平均能量载荷增加了5倍,而在行家情况下,平均能量载荷增加了3倍。但是,我们发现峰值增加了多达10倍,而与采用的速度踢模型无关。我们得出的结论是,包含失控的恒星可能会对矮星系的全球流出特性产生重大影响。

About ten to 20 percent of massive stars may be kicked out of their natal clusters before exploding as supernovae. These "runaway stars" might play a crucial role in driving galactic outflows and enriching the circumgalactic medium with metals. To study this effect, we carry out high resolution dwarf galaxy simulations that include velocity kicks to massive O/B stars above 8 M$_{\odot}$. We consider two scenarios, one that adopts a power law velocity distribution for kick velocities, resulting in more stars with high velocity kicks, and a more moderate scenario with a Maxwellian velocity distribution. We explicitly resolve the multi-phase interstellar medium (ISM), and include non-equilibrium cooling and chemistry channels. We adopt a resolved feedback scheme (\textsc{Griffin}) where we sample individual massive stars from an IMF. We follow the lifetime of these stars and add their photoionising radiation, their UV radiation field, and their photoelectric heating rate to the surrounding gas. At the end of their lifetime we explode the massive population as core collapse supernovae (CCSN). In the simulations with runaway massive stars, we add additional (natal) velocity kicks that mimic two and three body interactions that cannot be fully resolved in our simulations. We find that the inclusion of runaway or walkaway star scenarios has an impact on mass, metal, momentum and energy outflows as well as the respective loading factors. We find an increase in mass, metal and momentum loading by a factor of 2-3, whereas we find an increase in the mean energy loading by a factor of 5 in the runaway case and a factor of 3 in the walkaway case. However, we find that the peak values are increased by a factor of up to 10, independent of the adopted velocity kick model. We conclude that the inclusion of runaway stars could have a significant impact on the global outflow properties of dwarf galaxies.

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