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arXiv 1909.00832astro-ph.GA
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星系的局域光电离反馈效应

Local photoionization feedback effects on galaxies

Aura Obreja, Andrea V. Macciò, Benjamin Moster, Silviu M. Udrescu, Tobias Buck, Rahul Kannan, Aaron A. Dutton, Marvin Blank

摘要:

在N体SPH程序GASOLINE2中,我们对恒星和热气体的局部辐射场对气体加热和冷却的影响进行了光学薄近似。我们重新模拟了NIHAO计划中的三个星系:一个矮星系,一个银河系和一个大质量的螺旋星系,并研究了局部辐射场对星系性质的影响。我们还研究了不同的紫外线背景(UVB)模型的影响,通过运行相同的星系与两个不同的UVB。星系属性在$z=0$像恒星质量,恒星有效质量半径,HI质量,和径向范围的HI盘,显示显着的变化模型之间的局部辐射场,和两个UVB模型之间的差异较小。局部辐射场通过宇宙时间的内在效应是增加星系与其环星系介质(CGM)之间界面的平衡温度,将该边界向内移动,同时保持气体流入速率相对不变。因此,当考虑局部辐射源时,流入的温度增加。这种温度的增加是星系总质量的函数,对于大质量螺旋来说,CGM温度的中位数差为一个数量级。本地辐射场抑制恒星质量增长的$\sim$百分之二十的$z=0$的所有三个星系,而HI质量大约减半。气相图中的差异显著影响HI柱密度,使其分布中的峰向较低的$N_{\rm HI}$移动。

英文摘要:

We implement an optically thin approximation for the effects of the local radiation field from stars and hot gas on the gas heating and cooling in the N-body SPH code GASOLINE2. We resimulate three galaxies from the NIHAO project: one dwarf, one Milky Way-like and one massive spiral, and study what are the local radiation field effects on various galaxy properties. We also study the effects of varying the Ultra Violet Background (UVB) model, by running the same galaxies with two different UVBs. Galaxy properties at $z=0$ like stellar mass, stellar effective mass radius, HI mass, and radial extent of the HI disc, show significant changes between the models with and without the local radiation field, and smaller differences between the two UVB models. The intrinsic effect of the local radiation field through cosmic time is to increase the equilibrium temperature at the interface between the galaxies and their circumgalactic media (CGM), moving this boundary inwards, while leaving relatively unchanged the gas inflow rate. Consequently, the temperature of the inflow increases when considering the local radiation sources. This temperature increase is a function of total galaxy mass, with a median CGM temperature difference of one order of magnitude for the massive spiral. The local radiation field suppresses the stellar mass growth by $\sim$20 per cent by $z=0$ for all three galaxies, while the HI mass is roughly halfed. The differences in the gas phase diagrams, significantly impact the HI column densities, shifting their peaks in the distributions towards lower $N_{\rm HI}$.

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