AI 中文总结
研究利用信息论框架将恒星晕记忆作为银河系考古新可观测量，通过APOGEE数据，借助超额互信息等量化相关信息，构建记忆剖面及诊断量，发现不同记忆可观测量径向演化特点，为星系组装研究提供统一统计框架。
AI 中文摘要
银河系恒星晕保存着银河系组装历史的化石记录，但目前尚无统一框架来量化现今银河系中留存的此类信息。我们引入了一个信息论框架，将恒星晕记忆确立为银河系考古学中一个可直接测量的可观测量。利用APOGEE数据发布17中的晕星，通过超额互信息量化恒星动力学和化学可观测量之间共享的具有统计学意义的信息，实现基于物理动机分解为动力学、化学和交叉记忆库。我们构建累积径向记忆剖面以及两个无量纲诊断量，即记忆优势比和耦合效率，以研究留存的组装记忆在整个银河系晕中的分配情况。我们发现不同的记忆可观测量在晕内部呈现出不同的径向演化，但在约20千秒差距之外都朝着一个共同的具有统计学意义的残余记忆状态演化。与随机实现的比较表明，测量到的记忆比相应的零期望值大很多倍，证实它们代表真实的天体物理结构而非统计涨落。留存的组装记忆始终由动力学相关性主导，同时在整个晕中保持有限的化学 - 动力学耦合。这些结果表明，相混合重新分配而非完全抹去星系形成过程中留下的记忆印记。我们的研究将恒星晕记忆确立为银河系考古学的一个新可观测量，并为在观测和宇宙学模拟中研究星系组装提供了一个统一的统计框架。
英文摘要
The Galactic stellar halo preserves a fossil record of the Milky Way's assembly history, yet there is currently no unified framework for quantifying how much of this information survives in the present-day Galaxy. We introduce an information-theoretic framework that establishes stellar halo memory as a directly measurable observable for Galactic archaeology. Using APOGEE Data Release 17 halo stars, we quantify the statistically significant information shared among stellar dynamical and chemical observables through the excess mutual information, enabling a physically motivated decomposition into dynamical, chemical, and cross-memory reservoirs. We construct cumulative radial memory profiles together with two dimensionless diagnostics, the memory dominance ratio and the coupling efficiency, to investigate how the surviving assembly memory is partitioned throughout the Galactic halo. We find that the different memory observables exhibit distinct radial evolution in the inner halo but all evolve toward a common statistically significant residual memory state beyond $\sim 20$ kpc. Comparison with randomized realizations demonstrates that the measured memories exceed the corresponding null expectation by large factors, confirming that they represent genuine astrophysical structure rather than statistical fluctuations. The surviving assembly memory is consistently dominated by dynamical correlations while retaining a finite chemo-dynamical coupling across the halo. These results suggest that phase mixing redistributes, rather than completely erases, the memory imprinted during galaxy formation. Our study establishes stellar halo memory as a new observable for Galactic archaeology and provides a unified statistical framework for investigating galaxy assembly in both observations and cosmological simulations.
Comments8 pages, 3 figures, comments are welcome
