Balmer breaks in simulated galaxies at z>6
Balmer breaks in simulated galaxies at z>6
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DOI：
10.1093/mnras/stz2387
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发表时间：
2019-08
影响因子：
4.8
通讯作者：
C. Binggeli;E. Zackrisson;Xiangcheng Ma;A. Inoue;Anton Vikaeus;T. Hashimoto;K. Mawatari;I. Shimizu;D. Ceverino
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文献类型：
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作者：
C. Binggeli;E. Zackrisson;Xiangcheng Ma;A. Inoue;Anton Vikaeus;T. Hashimoto;K. Mawatari;I. Shimizu;D. Ceverino
对光谱证实的 z ≈ 9.1 星系 MACS1149-JD1 的光度观测表明，其光谱能量分布中存在显着的巴尔默断裂，这可能是由于其过去恒星形成活动的巨大波动所致。在本文中，我们研究了当代高红移星系的模拟在多大程度上产生了足够大的恒星形成率变化，以重现观察到的 MACS1149-JD1 的巴尔默断裂。我们发现几个独立的星系模拟无法解释推断大小的巴尔默断裂，这表明 MACS1149-JD1 要么一定是一种非常罕见的物体类型，要么我们的模拟缺少一些关键成分。我们提出了对 z ≈ 7-9 星系的光谱巴尔默断裂强度分布的预测，这些预测可以通过即将到来的詹姆斯·韦伯太空望远镜的观测进行测试，并讨论了关于尘埃变红、莱曼连续谱泄漏和标准恒星初始质量函数偏差的各种假设对结果的影响。
Photometric observations of the spectroscopically confirmed z ≈ 9.1 galaxy MACS1149-JD1 have indicated the presence of a prominent Balmer break in its spectral energy distribution, which may be interpreted as due to very large fluctuations in its past star formation activity. In this paper, we investigate to what extent contemporary simulations of high-redshift galaxies produce star formation rate variations sufficiently large to reproduce the observed Balmer break of MACS1149-JD1. We find that several independent galaxy simulations are unable to account for Balmer breaks of the inferred size, suggesting that MACS1149-JD1 either must be a very rare type of object or that our simulations are missing some key ingredient. We present predictions of spectroscopic Balmer break strength distributions for z ≈ 7–9 galaxies that may be tested through observations with the upcoming James Webb Space Telescope and also discuss the impact that various assumptions on dust reddening, Lyman continuum leakage and deviations from a standard stellar initial mass function would have on the results.