AI 中文总结
利用JWST数据研究红移3<z<7星系，通过SED拟合等得出物理性质，检测到20个星系有过量钠I D吸收，检测率随恒星质量等上升，等效宽度大，估计质量外流率，结论是中性外流在宇宙早期大质量星系中可能已存在且重要。
AI 中文摘要
最近詹姆斯·韦布空间望远镜/近红外光谱仪（JWST/NIRSpec）的观测表明，追踪中性气体外流的钠I D吸收在宇宙正午（z~2-3）的大质量星系中很普遍，但在更高红移处的情况仍 largely unexplored。本文利用来自公共DAWN JWST存档以及Mirage或Miracle调查的811个红移3<z<7的星系样本进行研究，这些星系具有可靠的光谱红移且其JWST/NIRSpec PRISM低分辨率光谱（R~100）中的连续谱信噪比>5。通过Prospector SED拟合得出物理性质和恒星形成历史，并通过减去最佳拟合恒星连续谱来分离每个光谱中的钠I D特征。在20个星系中检测到过量的钠I D吸收，几乎都在3<z<5且恒星质量>10^10 M⊙，总体检测率约为2.5%。检测率随恒星质量和静止状态急剧上升，在最大质量星系中达到约11%，在大质量熄灭系统中达到约43%。钠I D等效宽度很大，跨度为4至16埃，在尘埃丰富的恒星形成星系中最高。在先前的中分辨率观测中，等效宽度超过5埃的情况大多出现在外流气体中；因此，尽管PRISM分辨率下缺乏运动学信息，我们仍将检测结果解释为主要追踪中性外流。堆叠分析证实了这些趋势，并为不同子样本提供了平均钠I D等效宽度。在保守假设下，估计质量外流率为4至12 M⊙ yr^-1，约30%的检测星系超过当前恒星形成率。我们得出结论，中性外流在宇宙历史的前20亿年中可能已经存在于大质量星系中且很重要。
英文摘要
Recent JWST/NIRSpec observations have shown that Na I D absorption tracing neutral gas outflows is widespread in massive galaxies at Cosmic Noon ($z\sim2$-$3$), but their prevalence at higher redshift remains largely unexplored. Here we investigate whether similar outflows are already in place during the first 2 Gyr of cosmic history ($z>3$), using a sample of 811 galaxies at $3<z<7$ from the public DAWN JWST Archive and the Mirage or Miracle survey, with secure spectroscopic redshifts and continuum SNR$>5$ in their JWST/NIRSpec PRISM low-resolution spectra ($R\sim100$). We derived physical properties and star formation histories via Prospector SED fitting and isolated the Na I D feature in each spectrum by subtracting the best-fit stellar continuum. We detect an excess of Na I D absorption in 20 galaxies, almost all at $3<z<5$ with stellar mass $>10^{10} M_\odot$, an overall detection fraction of $\sim2.5\%$. The detection fraction rises steeply with stellar mass and quiescence, reaching $\sim11\%$ among the most massive galaxies and $\sim43\%$ among massive quenched systems. The Na I D equivalent widths are large, spanning 4 to 16 Angstrom, and are highest in dusty star-forming galaxies. In previous medium-resolution observations, EWs above 5 Angstrom were mostly found in outflowing gas; we thus interpret our detections as mostly tracing neutral outflows, despite the lack of kinematic information at PRISM resolution. A stacking analysis confirms these trends and provides average Na I D EWs for different subsamples. Under conservative assumptions, we estimate mass outflow rates of 4 to 12 $M_\odot$ yr$^{-1}$, exceeding the current star formation rate for about 30% of the detected galaxies. We conclude that neutral outflows are likely already present and important in massive galaxies during the first 2 Gyr of cosmic history.
Comments16 pages, 11 figures, 2 tables
