AI 中文总结
研究宇宙尘埃在星系演化初期的情况，通过thesan-zoom模拟套件分析，发现尘埃属性与爆发性恒星形成紧密相关，模型中爆发性恒星形成影响尘埃存活，预测衰减与观测有差异，未来高红移尘埃观测对理解相关物理机制至关重要。
AI 中文摘要
宇宙尘埃是星系演化的关键调节因素，但其在最初十亿年中的积累和存活情况仍受限制。我们对thesan-zoom辐射流体动力学放大模拟套件中的尘埃进行了系统分析，该模拟自洽地模拟了z≥3时星系中尘埃的形成、生长、破坏及其与辐射传输的耦合，多相星际介质和爆发性恒星形成历史。模拟星系再现了尘埃与气体以及尘埃与金属比率随气体金属度的观测趋势，同时在高特定恒星形成率下显示出尘埃不足。它们还大致匹配观测到的尘埃温度和紫外-红外空间偏移。我们发现尘埃及其属性具有强烈的时间变化性，并与爆发性恒星形成紧密相关，有短暂的红外明亮阶段（中位数持续时间为20.3^{+2.3}_{-2.4} Myr）和较长的贫尘埃阶段，自然地产生了尘埃温度与距恒星形成主序列距离之间的相关性。与观测相比，即使通过后处理包括未解析尘埃，预测的1500 Å处的衰减也较低，这表明需要一种能够使尘埃免受强反馈事件影响的机制，以使我们的星系形成模型与观测结果相协调。在我们的模型中，爆发性恒星形成阻止了大量尘埃储库（M_{dust} / M_{star}≥10^{-3}）在相当一部分宇宙时间内的存活。这意味着爆发性恒星形成只有在z~8（检测到大量尘埃储库的地方）迅速稳定下来，才能产生在z≥10时观测到的紫外明亮星系的过剩。也有可能我们的模型缺乏有助于尘埃存活的物理成分或涌现现象。未来对高红移尘埃的观测将是诊断第一批星系中起作用的物理机制的关键。
英文摘要
Cosmic dust is a key regulator of galaxy evolution, but its build-up and survival in the first billion years remain poorly constrained. We present a systematic analysis of dust in the thesan-zoom suite of radiation-hydrodynamical zoom-in simulations, which self-consistently model dust formation, growth, destruction, and its coupling to radiative transfer in galaxies at $z \geq 3$, a multi-phase ISM and bursty star formation histories. The simulated galaxies reproduce the observed trends of dust-to-gas and dust-to-metal ratios with gas metallicity, while showing a dust deficit at high specific star-formation rates. They also broadly match observed dust temperatures and UV-IR spatial offsets. We find that dust and its properties are strongly time-variable and tightly linked to bursty star formation, with short-lived IR-bright phases (median duration of $20.3^{+2.3}_{-2.4}$ Myr) and longer dust-poor phases, naturally producing a correlation between dust temperature and distance from the star-forming main sequence. The predicted attenuation at $1500$ Å is low compared to observations, even when including unresolved dust through post processing, indicating that a mechanism able to shield dust from strong feedback events is necessary to reconcile our galaxy formation model with observations. In our model, bursty star formation prevents the survival of large dust reservoirs ($M_{dust} / M_{star} \geq 10^{-3}$) over a significant fraction of cosmic time. This implies that bursty star formation can produce the observed overabundance of UV-bright galaxies at $z \geq 10$ only if it rapidly settles down by $z \sim 8$ (where large dust reservoirs are detected). It is also possible that our models lack physical ingredients or emergent phenomena that aid the survival of dust. Future observations of high-redshift dust will be key to diagnose the physical mechanism at play in the first galaxies.
Comments28 pages, submitted to the Open Journal of Astrophysics, comments welcome
