论文标题
大爆炸之后，明亮星系的年龄$ \ sim 500 $ MYR：与JWST $ z \ gtrsim 15 $的星级形成活动的见解
On the ages of bright galaxies $\sim 500$ Myr after the Big Bang: insights into star formation activity at $z \gtrsim 15$ with JWST
论文作者
论文摘要
有了JWST，研究早期宇宙中星系发展的新机会正在出现。 $ z \ gtrsim7 $星系对休息光特性的Spitzer限制证明了使用星系恒星质量和恒星形成历史（SFHS）的力量，以间接推断宇宙恒星形成历史。但是，只能用Spitzer检测到最明亮的单个$ z \ gtrsim8 $对象，这使得很难在$ z \ gtrsim10 $的情况下稳健地约束活动。在这里，我们利用JWST在$ z \ gtrsim8 $上大大提高的静息敏感性来限制七个UV-Bright（$ M_ {UV} \ Lessim-129.5 $）星系的年龄，被选为$ Z \ sim8.5-11 $，然后对$ z \ z \ gtrsim15 $ star的含义进行调查。我们推断出具有两个光谱能量分布建模代码的单个对象的属性，然后推断出明亮$ z \ sim8.5-11 $星系的年龄分布。我们发现中位年龄为$ \ sim20 $ myr，比以类似分析的$ z \ sim7 $推断出的年龄年龄，与早期较大特定的恒星形成率的发展一致。年龄分布表明，在$ z \ gtrsim15 $的情况下，只有$ \ sim3 $百分比的明亮$ z \ sim8.5-11 $ chalaxies的发光度也同样是发光的，这意味着，明亮星系的数量密度至少在$ z \ sim8.5-11 $和$ z \ sim15 $之间下降至少在$ z \ z \ z \ sim15 $之间。与一些早期的JWST结果调和，这种进化是具有挑战性的，表明鲜艳的星系的丰富性并不能显着减少在很早的时期，但如果在较旧的恒星组件的顶部形成年轻的恒星种群，则可能会缓解这种张力，或者如果在明亮的$ z \ sim15 $星系中观察到了恒星爆发，则可以缓解这种张力。
With JWST, new opportunities to study the evolution of galaxies in the early Universe are emerging. Spitzer constraints on rest-optical properties of $z\gtrsim7$ galaxies demonstrated the power of using galaxy stellar masses and star formation histories (SFHs) to indirectly infer the cosmic star formation history. However, only the brightest individual $z\gtrsim8$ objects could be detected with Spitzer, making it difficult to robustly constrain activity at $z\gtrsim10$. Here, we leverage the greatly improved rest-optical sensitivity of JWST at $z\gtrsim8$ to constrain the ages of seven UV-bright ($M_{UV}\lesssim-19.5$) galaxies selected to lie at $z\sim8.5-11$, then investigate implications for $z\gtrsim15$ star formation. We infer the properties of individual objects with two spectral energy distribution modelling codes, then infer a distribution of ages for bright $z\sim8.5-11$ galaxies. We find a median age of $\sim20$ Myr, younger than that inferred at $z\sim7$ with a similar analysis, consistent with an evolution towards larger specific star formation rates at early times. The age distribution suggests that only $\sim3$ percent of bright $z\sim8.5-11$ galaxies would be similarly luminous at $z\gtrsim15$, implying that the number density of bright galaxies declines by at least an order of magnitude between $z\sim8.5-11$ and $z\sim15$. This evolution is challenging to reconcile with some early JWST results suggesting the abundance of bright galaxies does not significantly decrease towards very early times, but we suggest this tension may be eased if young stellar populations form on top of older stellar components, or if bright $z\sim15$ galaxies are observed during a burst of star formation.
