论文标题
与JWST一起对ISM的最初洞察：高[O III] $ \ MATHBF {λ4363} $/[O III] $ \ MATHBF {λ5007} $的物理含义。
First Insights into the ISM at $z>8$ with JWST: Possible Physical Implications of a High [O III]$\mathbf{λ4363}$/[O III]$\mathbf{λ5007}$
论文作者
论文摘要
我们对三个光谱镜确认的星系$ z> 7.5 $的剩余帧光发射线比率进行了详细分析。星系是在James Webb太空望远镜（JWST）的早期发布观察结果SMACS J0723.3 $ - $ 7327中确定的。通过定量比较这些星系的Balmer和氧线比与各种低红移“模拟”种群（例如绿豌豆，蓝莓等）进行了比较，我们表明，没有单个模拟人群捕获了在$ z> 7.5 $处观察到的所有三个星系的多样性。我们发现$ z = 7.67 $和$ z = 7.66 $的S06355与当地的绿豌豆和蓝莓相似。相比之下，$ z = 8.50 $的S04590似乎与其他两个星系有显着差异，大多数类似于本地宇宙中极低的金属系统。 S04590中最引人注目的光谱功能也许是奇怪的是[O III] $ \ lambda4363 $/[O III] $ \ lambda5007 $ ratio $ ratio $ 0.048 $（或$ 0.055 $ $ 0.055 $时，灰尘相交时），请暗示，$ \ sim $ \ sim of sim of sim pers of sim f \ sim f \ sim pers of sim pers of sim pripe \ sim pert \ sim3 k. $> 10^4 \ {\ rm cm^{ - 3}} $。观察到的线比表明该星系不太可能托管AGN。使用光电离模型，我们表明，除了年轻的，低金属性的恒星种群外，还包含高质量X射线二进制文件或高宇宙射线背景，还可以提供所需的额外加热，以解释观察到的高RO3，同时与其他观察到的线路比率保持一致。我们的模型是准确表征非常高红移和加热的主要来源的第一步，这表明当我们更深入地探究电离时代时，非热过程可能变得很重要。
We present a detailed analysis of the rest-frame optical emission line ratios for three spectroscopically confirmed galaxies at $z>7.5$. The galaxies were identified in the James Webb Space Telescope (JWST) Early Release Observations field SMACS J0723.3$-$7327. By quantitatively comparing Balmer and oxygen line ratios of these galaxies with various low-redshift "analogue" populations (e.g. Green Peas, Blueberries, etc.), we show that no single analogue population captures the diversity of line ratios of all three galaxies observed at $z>7.5$. We find that S06355 at $z=7.67$ and S10612 at $z=7.66$ are similar to local Green Peas and Blueberries. In contrast, S04590 at $z=8.50$ appears to be significantly different from the other two galaxies, most resembling extremely low-metallicity systems in the local Universe. Perhaps the most striking spectral feature in S04590 is the curiously high [O III] $\lambda4363$/[O III] $\lambda5007$ ratio (RO3) of $0.048$ (or $0.055$ when dust-corrected), implying either extremely high electron temperatures, $\sim3\times10^4$ K, or gas densities $>10^4\ {\rm cm^{-3}}$. Observed line ratios indicate that this galaxy is unlikely to host an AGN. Using photoionization modelling, we show that the inclusion of high-mass X-ray binaries or a high cosmic ray background in addition to a young, low-metallicity stellar population can provide the additional heating necessary to explain the observed high RO3 while remaining consistent with other observed line ratios. Our models represent a first step at accurately characterising the dominant sources of photoionization and heating at very high redshifts, demonstrating that non-thermal processes may become important as we probe deeper into the Epoch of Reionization.
