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arXiv 2412.02439astro-ph.GAcs.LGstat.MEstat.ML
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星系形成中的先天与后天:利用因果机器学习研究环境对恒星形成的影响

Nature versus nurture in galaxy formation: the effect of environment on star formation with causal machine learning

University College London(伦敦大学学院);University of Geneva(日内瓦大学);Spotify

Sunil Mucesh, William G. Hartley, Ciarán M. Gilligan-Lee, Ofer Lahav

AI总结:

本文在 IllustrisTNG 模拟中用因果机器学习估计环境对恒星形成率的影响,发现其作用随红移由强抑制转为增强,并厘清了先天与后天因素。

摘要:

理解星系如何形成和演化是现代天文学的核心。随着大规模巡天和模拟的出现,过去几十年取得了显著进展。尽管如此,这些现象背后的物理过程,尤其是它们的重要性,仍远未被弄清,因为人们主要确立的是相关性,而非潜在因果关系。我们通过应用因果推断框架来应对这一挑战。具体而言,我们在 IllustrisTNG 模拟中估计环境对恒星形成率的因果效应,从而探讨星系形成和演化究竟更多取决于先天(即内部过程)还是后天(即外部过程)这一根本性开放问题。为此,我们开发了一个综合因果模型,并采用来自流行病学的前沿技术,以克服区分先天与后天这一长期存在的问题。我们发现因果效应为负且十分显著,环境使 SFR 最多受到约 100 倍的抑制。虽然在 z=0 时总体效应为负,但在早期宇宙中,环境被发现具有正向影响:在 z~1 时使恒星形成增强约 10 倍,而在更高红移处增强幅度甚至更大。此外,我们表明:(i)先天也发挥重要作用,因为忽略先天会使中等密度环境中的因果效应被低估约 2 倍;(ii)像文献中常见的那样控制某一快照时刻的恒星质量,不仅不足以区分先天和后天,实际上还会产生不利影响;不过(iii)恒星质量是先天效应的适当代理。最后,这项工作或许能成为一份有用的蓝图,用于在其他处理具有闭合反馈环的动态系统的领域中提取因果洞见,例如地球气候。

英文摘要:

Understanding how galaxies form and evolve is at the heart of modern astronomy. With the advent of large-scale surveys and simulations, remarkable progress has been made in the last few decades. Despite this, the physical processes behind the phenomena, and particularly their importance, remain far from known, as correlations have primarily been established rather than the underlying causality. We address this challenge by applying the causal inference framework. Specifically, we tackle the fundamental open question of whether galaxy formation and evolution depends more on nature (i.e., internal processes) or nurture (i.e., external processes), by estimating the causal effect of environment on star-formation rate in the IllustrisTNG simulations. To do so, we develop a comprehensive causal model and employ cutting-edge techniques from epidemiology to overcome the long-standing problem of disentangling nature and nurture. We find that the causal effect is negative and substantial, with environment suppressing the SFR by a maximal factor of $\sim100$. While the overall effect at $z=0$ is negative, in the early universe, environment is discovered to have a positive impact, boosting star formation by a factor of $\sim10$ at $z\sim1$ and by even greater amounts at higher redshifts. Furthermore, we show that: (i) nature also plays an important role, as ignoring it underestimates the causal effect in intermediate-density environments by a factor of $\sim2$, (ii) controlling for the stellar mass at a snapshot in time, as is common in the literature, is not only insufficient to disentangle nature and nurture but actually has an adverse effect, though (iii) stellar mass is an adequate proxy of the effects of nature. Finally, this work may prove a useful blueprint for extracting causal insights in other fields that deal with dynamical systems with closed feedback loops, such as the Earth's climate.

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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