COLD ACCRETION IN EARLY GALAXY FORMATION AND ITS Ly &agr; ?> SIGNATURES
COLD ACCRETION IN EARLY GALAXY FORMATION AND ITS Ly &agr; ?> SIGNATURES
复制标题
早期星系形成中的冷吸积及其 Ly
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Tom Abel
中科院分区：
文献类型：
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作者：
H. Yajima;Yue;Qirong Zhu;Tom Abel
Lyα发射在探测高红移星系方面发挥了重要作用，包括最近在红移z bbbb70 ？>。它还可能包含有关这些星系起源的重要信息。在这里，我们研究了一个典型的L*星系的形成及其最早阶段的观测特征，通过将宇宙流体动力学模拟与三维辐射传输（RT）计算相结合，使用新改进的ART 2 ？>代码。我们的宇宙学模拟使用了Aquila初始条件，它以高分辨率放大了一个类似银河系的光环，我们的RT耦合了多波长连续体、Lyα线和氢的电离。我们发现，通过冷气体的有效吸积，模型星系在红移z ~ 24处开始形成，产生了光度为L Ly &agr的强Lyα线；~ 10 42 erg s - 1 ？>早在z ~ 14。Lyα的发射似乎是在追踪这种冷而致密的气体。线条呈现不对称的单峰轮廓，并移向蓝色翼，这是气体流入的特征。此外，激发冷却对Lyα总光度的贡献随着红移的增加而增加，并在z > 6时占主导地位。我们预测，在合理的积分时间内，詹姆斯韦伯太空望远镜和阿塔卡马大型毫米波阵列可能会在z > 8处探测到L*星系。然而，在红移12之外，Lyα线可能只能通过光谱调查观察到。我们的研究结果表明，Lyα线是探测第一代星系并破译其形成机制的最有力工具之一。
Lyα emission has played an important role in detecting high-redshift galaxies, including recently distant ones at redshifts z > 7 ?> . It may also contain important information concerning the origin of these galaxies. Here, we investigate the formation of a typical L* galaxy and its observational signatures at the earliest stage by combining a cosmological hydrodynamic simulation with three-dimensional radiative transfer (RT) calculations using the newly improved ART 2 ?> code. Our cosmological simulation uses the Aquila initial condition, which zooms in on a Milky-Way-like halo with high resolutions, and our RT couples multi-wavelength continuum, Lyα line, and ionization of hydrogen. We find that the modeled galaxy starts to form at redshift z ∼ 24 through the efficient accretion of cold gas, which produces a strong Lyα line with a luminosity of L Ly &agr; ∼ 10 42 erg s - 1 ?> as early as z ∼ 14. The Lyα emission appears to trace the cold, dense gas. The lines exhibit asymmetric, single-peak profiles, and are shifted to the blue wing, a characteristic feature of gas inflow. Moreover, the contribution to the total Lyα luminosity from excitation cooling increases with redshift and becomes dominant at z ≳ 6. We predict that L* galaxies such as the modeled one may be detected at z ≲ 8 by the James Webb Space Telescope and Atacama Large Millimeter Array with a reasonable integration time. Beyond redshift 12, however, the Lyα line may only be observable by spectroscopic surveys. Our results suggest that the Lyα line is one of the most powerful tools to detect the first generation of galaxies and decipher their formation mechanism.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.