论文标题
鹰模拟中的银河流入和风回收率
Galactic inflow and wind recycling rates in the EAGLE simulations
论文作者
论文摘要
银河风回收的作用代表了银河系进化中最大的未知数之一，因为回收对银河系生长的任何贡献都随着首次插入材料的流入速率而在很大程度上退化，而流出的气体和金属的速率则由星系驱动。我们介绍了从Eagle Cosmological Simulation项目中对风回收效率的测量，利用了重现现实的星系人群的大容量模拟的统计能力。我们研究了在光环尺度上的风回收，即已弹出的气体超出了光环病毒半径，并且在星系尺度上，即从ISM弹出的气体至少$ \ \ \ \ \ \ \ 10 \，大约10 \，\％\％$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $（因此，较小的银色银行式壁炉架）。 Galaxy尺度的风回收通常效率低下，具有比哈勃时间的特征返回时间尺度相当或更长，并且效率显然在特征性的光晕质量上达到$ m_ {200} = 10^{12} {12}} {12}} \，\ Mathrm {m_ \ odot} $。相应地，大多数气体被吸收到Eagle的星系上，这是第一次进入。在光晕量表上，回收在光环上的效率与半分析星系形成模型假设的值的数量级不同。目前难以评估风能循环效率与其他流体动力学模拟的效率差异，但可能较小。我们能够证明，在鹰中，风回收对星系生长的分数贡献要小于其他模拟。我们发现，相对于质量光环的暗物质积聚的预期，$ m_ {200} <10} <10} <10^{12} \，\ mathrm {m_ mathrm {m_ \ odot} $，累积的初次气体积聚率降低了，表明对晕筒量表的有效预防反馈。
The role of galactic wind recycling represents one of the largest unknowns in galaxy evolution, as any contribution of recycling to galaxy growth is largely degenerate with the inflow rates of first-time infalling material, and the rates with which outflowing gas and metals are driven from galaxies. We present measurements of the efficiency of wind recycling from the EAGLE cosmological simulation project, leveraging the statistical power of large-volume simulations that reproduce a realistic galaxy population. We study wind recycling at the halo scale, i.e. gas that has been ejected beyond the halo virial radius, and at the galaxy scale, i.e. gas that has been ejected from the ISM to at least $\approx 10 \, \%$ of the virial radius (thus excluding smaller-scale galactic fountains). Galaxy-scale wind recycling is generally inefficient, with a characteristic return timescale that is comparable or longer than a Hubble time, and with an efficiency that clearly peaks at the characteristic halo mass of $M_{200} = 10^{12} \, \mathrm{M_\odot}$. Correspondingly, the majority of gas being accreted onto galaxies in EAGLE is infalling for the first time. At the halo scale, the efficiency of recycling onto haloes differs by orders of magnitude from values assumed by semi-analytic galaxy formation models. Differences in the efficiency of wind recycling with other hydrodynamical simulations are currently difficult to assess, but are likely smaller. We are able to show that the fractional contribution of wind recycling to galaxy growth is smaller in EAGLE than in some other simulations. We find that cumulative first-time gas accretion rates at the virial radius are reduced relative to the expectation from dark matter accretion for haloes with mass, $M_{200} < 10^{12} \, \mathrm{M_\odot}$, indicating efficient preventative feedback on halo scales.
