THE FIRST GALAXIES: ASSEMBLY OF DISKS AND PROSPECTS FOR DIRECT DETECTION
THE FIRST GALAXIES: ASSEMBLY OF DISKS AND PROSPECTS FOR DIRECT DETECTION
复制标题
第一个星系：圆盘的集合和直接探测的前景
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
V. Bromm
中科院分区：
文献类型：
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作者：
A. Pawlik;M. Milosavljevic;V. Bromm
詹姆斯·韦伯太空望远镜（JWST）将能够观测到红移z ~ 10的星系，从而使我们能够在很早的时候测试我们目前对结构形成的理解。先前的工作已经表明，在晕内的第一批星系，在z > 10的温度为Tvir > 104 K，质量为Mvir > 108 M☉，可能太暗了，至少是一个数量级，即使在JWST的深度曝光中也无法探测到。因此，JWST收集的光可能主要来自10倍大质量光晕内的星系的辐射。我们使用宇宙学缩放平滑粒子流体动力学模拟来研究这些星系的集合，并评估JWST的可观测性。我们比较了两种完全相同的模拟，除了包含非平衡H/D化学和分子氢的辐射冷却。在这两种模拟中，光晕气体的很大一部分沉淀在两个嵌套的、扩展的气体盘中，这些气体盘围绕着一个致密的大质量气体核心。氢分子的存在使得盘状气体可以达到低温并形成明显的螺旋结构，但不会从质量上改变其抗破碎的稳定性。我们将恒星形成的理想模型与恒星群合成模型相结合，对模拟星系进行后处理，以估计星云重组线和紫外线连续体的光度。我们证明，JWST将能够约束星系中恒星种群的性质，如基于He1640重组线的探测所模拟的。将我们的结果外推到质量低于或高于模拟结果的光晕，表明JWST可能会在未来对z > 10宇宙的深度曝光中发现多达1000个恒星爆发星系。
The James Webb Space Telescope (JWST) will enable observations of galaxies at redshifts z ≳ 10 and hence allow us to test our current understanding of structure formation at very early times. Previous work has shown that the very first galaxies inside halos with virial temperatures Tvir ≲ 104 K and masses Mvir ≲ 108 M☉ at z ≳ 10 are probably too faint, by at least one order of magnitude, to be detected even in deep exposures with JWST. The light collected with JWST may therefore be dominated by radiation from galaxies inside 10 times more massive halos. We use cosmological zoomed smoothed particle hydrodynamics simulations to investigate the assembly of such galaxies and assess their observability with JWST. We compare two simulations that are identical except for the inclusion of non-equilibrium H/D chemistry and radiative cooling by molecular hydrogen. In both simulations a large fraction of the halo gas settles in two nested, extended gas disks which surround a compact massive gas core. The presence of molecular hydrogen allows the disk gas to reach low temperatures and to develop marked spiral structure but does not qualitatively change its stability against fragmentation. We post-process the simulated galaxies by combining idealized models for star formation with stellar population synthesis models to estimate the luminosities in nebular recombination lines as well as in the ultraviolet continuum. We demonstrate that JWST will be able to constrain the nature of the stellar populations in galaxies such as simulated here based on the detection of the He1640 recombination line. Extrapolation of our results to halos with masses both lower and higher than those simulated shows that JWST may find up to a thousand star-bursting galaxies in future deep exposures of the z ≳ 10 universe.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.