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arXiv 2603.05930astro-ph.GAastro-ph.CO
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暗物质晕结构与星系形态的受控实验 I:什么决定了星系大小?

Controlled Experiments on Dark-Matter Halo Structure and Galaxy Morphology I: What Sets Galaxy Sizes?

Peking University(北京大学);Kavli Institute for Astronomy and Astrophysics, Peking University(北京大学科维理天文与天体物理研究所)

Guangze Sun, Fangzhou Jiang, Jing Wang

AI总结:

通过受控模拟,量化了在固定晕质量下,晕自旋、浓度、内密度轮廓和重子分数对星系大小的影响,发现晕浓度是最重要的预测因子。

摘要:

星系的性质与其宿主暗物质晕的特征密切相关。我们使用一套孤立场系的受控模拟,在固定晕质量$M_{\rm{vir}}=10^{11} M_\odot$下,量化了晕自旋、浓度、内密度轮廓和重子分数如何调节星系大小。我们生成晕的初始条件以及平衡的球形气体分布,参数网格由这四个晕参数张成,并使用$\texttt{GIZMO}$代码和$\texttt{FIRE-3}$物理演化系统。得到的恒星和冷重子的半质量半径系统地依赖于晕结构和重子含量:星系大小随晕自旋增加而增大,随晕浓度增加而减小,对内密度斜率不敏感(除非在高度尖点晕中),并在高重子分数下被强烈抑制。我们使用不同指标(包括二次响应曲面方法和随机森林回归)评估晕参数对星系大小的相对重要性,一致发现晕浓度是最具信息量的预测因子。重子分数通过调节星系大小对晕自旋的依赖性,对大小显示出微妙的非单调影响。我们的结果阐明了宿主暗物质晕的哪些次级参数主导了巨矮星质量尺度上星系大小的弥散。

英文摘要:

The properties of galaxies are intricately linked to the characteristics of their host dark-matter haloes. We use a suite of controlled simulations of isolated galaxies to quantify how halo spin, concentration, inner density profile, and baryon fraction regulate galaxy sizes, at fixed halo mass of $M_{\rm{vir}}=10^{11} M_\odot$. We generate initial conditions of haloes and inhabitant spherical gas distributions in equilibrium, on a parameter grid spanned by these four halo parameters, and evolve the systems with the $\texttt{GIZMO}$ code and the $\texttt{FIRE-3}$ physics. The resulting half-mass radii of stars and cold baryons depend systematically on halo structure and baryon content: galaxy size increases with halo spin, decreases with halo concentration, is weakly sensitive to the inner density slope except in highly cuspy haloes, and is strongly suppressed at high baryon fractions. We evaluate the relative importance of the halo parameters on galaxy size using different metrics including the quadratic response-surface method and random-forest regression, and consistently find halo concentration to be the most informative predictor of size. The baryon fraction shows a subtle, non-monotonic impact on size, by modulating how galaxy size depends on halo spin. Our results clarify which secondary parameters of host dark-matter haloes dominate the scatter in galaxy sizes at the massive-dwarf mass scale.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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