SERENADE III：深入探究 z≳6 时高尘埃温度与高 [O III]/[C II] 比值的起源

本文分析了九个高红移莱曼断裂星系的阿塔卡马大型毫米/亚毫米波阵（ALMA）高频观测数据，旨在约束 z≳6 星系的尘埃温度。研究发现，低金属度环境下的尘埃屏蔽减弱及加热效率提升导致了较高的尘埃温度，且该温度与比恒星形成率及金属度密切相关。此外，高气体密度下的碰撞去激发作用解释了高红移星系中 [CII] 发射线相对较弱的现象。

arXiv:2608.26708v1 Announce Type: new Abstract: We present an analysis of ALMA high-frequency observations of nine bright Lyman-break galaxies at $5.8<8.3$. Our sample consists of five galaxies at $z\sim6$ newly observed in Band-9 and/or 10, allowing us to better constrain the dust temperature ($T_{\rm dust}$) in a statistical sample of $z\gtrsim6$ galaxies. Our measurements of the dust temperature at $z\sim6-9$ suggest most of the star-forming galaxies show $T_{\rm dust}\sim40\,{\rm K}$ on average, whereas three galaxies show significantly higher $T_{\rm dust}$ ($\gtrsim60\,{\rm K}$). We find a potential negative correlation between $T_{\rm dust}$ and gas-phase metallicity with $T_{\rm dust}\propto Z^{-0.50\pm0.19}$, implying decreased dust shielding and efficient dust heating in low-metallicity environments. Given the systematic offset of $T_{\rm dust}$ between $z\sim0$ and $z\sim6-9$ at fixed metallicity, we find $T_{\rm dust}$ is well described by sSFR as well as $Z$ with $\log T_{\rm dust}=-0.25^{+0.03}_{-0.04}\times(\log Z-0.57\times\log {\rm sSFR})+4.88^{+0.47}_{-0.43}$ across $z\sim0$ to $z\sim6-9$. Simultaneously with the dust continuum, these observations cover the [OI]63$\mu$m emission line for five galaxies, which traces dense neutral gas. We find a lower [CII]/[OI] ratio in $z\gtrsim6$ galaxies than in local samples, suggesting that [CII] becomes fainter due to collisional de-excitation at high gas density. Combining the [OI], [OIII], and [CII] lines and