Modelling chemical abundance distributions for dwarf galaxies in the Local Group: the impact of turbulent metal diffusion
Modelling chemical abundance distributions for dwarf galaxies in the Local Group: the impact of turbulent metal diffusion
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模拟本星系群中矮星系的化学丰度分布：湍流金属扩散的影响
DOI：
10.1093/mnras/stx2858
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发表时间：
2017
影响因子：
4.8
通讯作者：
Quataert, Eliot
中科院分区：
文献类型：
--
作者：
Escala, Ivanna;Wetzel, Andrew;Kirby, Evan N;Hopkins, Philip F;Ma, Xiangcheng;Wheeler, Coral;Kereš, Dušan;Faucher-Giguère, Claude-André;Quataert, Eliot
我们研究了FIRE项目中矮星系中恒星金属丰度分布函数（MDF），包括Fe和α元素丰度。我们研究孤立的矮星系和那些银河系质量的星系的卫星。特别是，我们研究的影响，包括一个亚网格湍流模型的金属在气体中的扩散。包括扩散的模拟具有较窄的MDF和丰度比分布，因为扩散将单个气体和星星粒子推向平均金属丰度。这种效应与本星系群矮星系中观测到的丰度分布有更好的一致性，包括[α/Fe]与[Fe/H]的微小内禀散射，其值为1.01 dex。在我们的模拟中出现这种小的内在散射，因为矮星系中的星际介质在几乎所有的宇宙时间都是很好的混合的，因此在给定时间形成的恒星具有类似于10.1 dex的丰度。因此，大多数的散射丰度atz= 0产生的红移的演变，而不是在ISM的瞬时散射。我们发现卫星和孤立的矮星系，这表明环境的影响发挥了较小的作用相比，在我们的模拟内部的化学演化类似的宽度和内在的散射。总的来说，包括金属扩散，我们的模拟再现了观测到的低质量星系的丰度分布宽度，使详细研究化学演化的星系形成。
We investigate stellar metallicity distribution functions (MDFs), including Fe and α-element abundances, in dwarf galaxies from the Feedback in Realistic Environment (FIRE) project. We examine both isolated dwarf galaxies and those that are satellites of a Milky Way-mass galaxy. In particular, we study the effects of including a sub-grid turbulent model for the diffusion of metals in gas. Simulations that include diffusion have narrower MDFs and abundance ratio distributions, because diffusion drives individual gas and star particles towards the average metallicity. This effect provides significantly better agreement with observed abundance distributions in dwarf galaxies in the Local Group, including small intrinsic scatter in [α/Fe] versus [Fe/H] of ≲0.1 dex. This small intrinsic scatter arises in our simulations because the interstellar medium in dwarf galaxies is well mixed at nearly all cosmic times, such that stars that form at a given time have similar abundances to ≲0.1 dex. Thus, most of the scatter in abundances atz= 0 arises from redshift evolution and not from instantaneous scatter in the ISM. We find similar MDF widths and intrinsic scatter for satellite and isolated dwarf galaxies, which suggests that environmental effects play a minor role compared with internal chemical evolution in our simulations. Overall, with the inclusion of metal diffusion, our simulations reproduce abundance distribution widths of observed low-mass galaxies, enabling detailed studies of chemical evolution in galaxy formation.