Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions
Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions
复制标题
寡头的快速再电离：具有高逃逸分数的大质量、紫外光、恒星形成星系的案例
作者：
R. Naidu;S. Tacchella;C. Mason;S. Bose;P. Oesch;C. Conroy
宇宙最后一次大相变--宇宙再电离--的主角仍然难以捉摸。微弱的恒星形成星系是领先的候选星系，因为它们被发现数量众多，可能具有显著的电离光子逃逸分数()。在这里，我们通过一个经验模型来更新这张图片，该模型成功地预测了最新的观测结果(例如，恒星形成密度(AT)的快速下降)。我们为我们的模型中的每个星系生成一个电离谱，并通过利用再电离时间线的最新测量结果(例如，z>；7处类星体和星系的Lyα衰减)进行约束。假设z>；6的所有源都是一个常数，我们发现<；−13.5星系需要，才能完成再电离。推算出的星系间介质中性分数为[0.9，0.5，0.1]at，也就是说，在z>；8ρsfr的驱动下，大部分再电离在300Myr内迅速发生，并受到z∼7-8处测量到的高中性分数(∼60%-90%)的青睐。受横跨z∼0-6.6时的莱曼连续介质(LYC)泄漏的紧急样本的启发，我们提出了一个与发现和发现有关的物理激励模型。由于落在z=8和z=0之间的∼2.5dex，我们的模型解释了在z>；6时红移较低时的微不足道的上限，以及它所需的演化到∼0.2时。在这个模型中，引人注目的是，具有<；−18和LOG(M⋆/M⊙)>；8的星系中有<；5%的星系占再电离预算的80%-这与由大量微弱来源领导的经典的“民主”再电离截然不同。事实上，弱源(>；−16)必须降级为有限的作用，以确保z=7-8处的高中性分数。UV光度函数(>；−2)的浅弱末端斜率和/或向大质量星系倾斜的分布会产生所需的延迟和快速再电离。我们预测，像CoLa1(z=6.6，∼30%，=−21.5)这样的LyC泄漏者将在z∼6变得越来越常见，再电离的驱动因素并不隐藏在光度函数的微弱末端，而是我们已经知道的。
The protagonists of the last great phase transition of the universe—cosmic reionization—remain elusive. Faint star-forming galaxies are leading candidates because they are found to be numerous and may have significant ionizing photon escape fractions ( ). Here we update this picture via an empirical model that successfully predicts latest observations (e.g., the rapid drop in star-formation density ( at ). We generate an ionizing spectrum for each galaxy in our model and constrain by leveraging latest measurements of the reionization timeline (e.g., Lyα damping of quasars and galaxies at z > 7). Assuming a constant across all sources at z > 6, we find < −13.5 galaxies need = to complete reionization. The inferred Intergalactic Medium neutral fraction is [0.9, 0.5, 0.1] at —that is, the bulk of reionization transpires rapidly in 300 Myr, driven by the z > 8 ρSFR and favored by high neutral fractions (∼60%–90%) measured at z ∼ 7–8. Inspired by the emergent sample of Lyman Continuum (LyC) leakers spanning z ∼ 0–6.6 that overwhelmingly displays higher-than-average star-formation surface density ( ), we propose a physically motivated model relating to and find . Since falls by ∼2.5 dex between z = 8 and z = 0, our model explains the humble upper limits on at lower redshifts and its required evolution to ∼ 0.2 at z > 6. Within this model, strikingly, <5% of galaxies with < −18 and log(M⋆/M⊙) > 8 (the “oligarchs”) account for ≳80% of the reionization budget—a stark departure from the canonical “democratic” reionization led by copious faint sources. In fact, faint sources ( > −16) must be relegated to a limited role in order to ensure high neutral fractions at z = 7–8. Shallow faint-end slopes of the UV luminosity function ( > −2) and/or distributions skewed toward massive galaxies produce the required late and rapid reionization. We predict that LyC leakers like COLA1 (z = 6.6, ∼ 30%, = −21.5) will become increasingly common toward z ∼ 6 and that the drivers of reionization do not lie hidden across the faint end of the luminosity function but are already known to us.
影响因子：
4.8
作者：
C. Mason;A. Fontana;T. Treu;K. Schmidt;A. Hoag;L. Abramson;R. Amorín;M. Bradač;L. Guaita
通讯作者：
C. Mason;A. Fontana;T. Treu;K. Schmidt;A. Hoag;L. Abramson;R. Amorín;M. Bradač;L. Guaita
影响因子：
4.8
作者：
R. Endsley;P. Behroozi;D. Stark;C. Williams;B. Robertson;M. Rieke;S. Gottlöber;G. Yepes
通讯作者：
R. Endsley;P. Behroozi;D. Stark;C. Williams;B. Robertson;M. Rieke;S. Gottlöber;G. Yepes
DOI：
10.3847/1538-4357/ab1de7
发表时间：
2019-01
期刊：
The Astrophysical Journal
影响因子：
--
作者：
A. Hoag;M. Bradavc;K. Huang;C. Mason;T. Treu;K. Schmidt;M. Trenti;V. Strait;B. Lemaux;E. Finney;Maia Paddock
通讯作者：
A. Hoag;M. Bradavc;K. Huang;C. Mason;T. Treu;K. Schmidt;M. Trenti;V. Strait;B. Lemaux;E. Finney;Maia Paddock