检验部分遍历性作为孤立星系中恒星形成偏离星系主序的预测因子
Examining partial ergodicity as a predictor of star formation departures from the galactic main sequence in isolated galaxies
AI总结：
本研究通过观测启发的孤立星系模拟，检验部分遍历性作为恒星形成偏离主序的预测因子，发现完全遍历性被排除，但存在部分遍历性证据，平均最大偏差0.20 dex，首次在天文中应用该概念。
摘要：
由于缺乏在宇宙学时间尺度上追踪单个星系的能力，我们对单个星系演化的理解大体上是从群体趋势和行为中推断出来的。在其最具限制性的形式中，这种方法假设星系恒星形成特性表现出遍历性，从而可以通过系综行为统计推断单个星系的演化。我们通过使用观测启发的孤立星系模拟来检验这一假设的有效性。该模拟星系系列通过核密度估计构建结构参数分布，并在必要时辅以理论关系，以统计方式构建以匹配观测到的星系特性。我们还测试了不同物理过程（如恒星风或暗物质晕亚结构的存在）对恒星形成行为的影响。我们考虑了约束遍历特性时涉及的微妙之处，例如由恒星风反馈强加的平稳性与真正遍历行为之间的区别。然而，若恒星形成特性缺乏足够的变异性，单个星系便无法探索完整的参数空间。尽管如预期那样，完全遍历性似乎被排除，但我们发现了部分遍历性的合理证据，即对按质量选择的星系子集进行平均更广泛地类似于时间平均，其中各物理场景下的平均最大偏差为0.20 dex。据我们所知，这是首次在天文学背景下考虑部分遍历性，并提供了一个有前景的统计概念。尽管暗物质亚结构近距离遭遇引入了形态变化，但未发现亚晕会显著增加对遍历性假设的偏离。
英文摘要：
Lacking the ability to follow individual galaxies on cosmological timescales, our understanding of individual galaxy evolution is broadly inferred from population trends and behaviours. In its most prohibitive form, this approach assumes that galactic star formation properties exhibit ergodicity, so that individual galaxy evolution can be statistically inferred via ensemble behaviours. The validity of this assumption is tested through the use of observationally motivated simulations of isolated galaxies. The suite of simulated galaxies is statistically constructed to match observed galaxy properties by using kernel density estimation to create structural parameter distributions, augmented by theoretical relationships where necessary. We also test the impact of different physical processes, such as stellar winds or the presence of halo substructure on the star formation behaviour. We consider the subtleties involved in constraining ergodic properties, such as the distinction between stationarity imposed by stellar wind feedback and truly ergodic behaviour. However, without sufficient variability in star formation properties, individual galaxies are unable to explore the full parameter space. While, as expected, full ergodicity appears to be ruled out, we find reasonable evidence for partial ergodicity, where averaging over mass-selected subsets of galaxies more broadly resembles time averages, where the average largest deviation across physical scenarios is 0.20 dex. As far as we are aware, this the first time partial ergodicity has been considered in an astronomical context, and provides a promising statistical concept. Despite morphological changes introduced by close encounters with dark matter substructure, subhaloes are not found to significantly increase deviations from ergodic assumptions.
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