The thesan project: ionizing escape fractions of reionization-era galaxies
The thesan project: ionizing escape fractions of reionization-era galaxies
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论文项目：再电离时代星系的电离逃逸部分
DOI：
10.1093/mnras/stad210
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发表时间：
2023
影响因子：
4.8
通讯作者：
Hernquist, Lars
中科院分区：
文献类型：
--
作者：
Yeh, Jessica Y-C;Smith, Aaron;Kannan, Rahul;Garaldi, Enrico;Vogelsberger, Mark;Borrow, Josh;Pakmor, Rüdiger;Springel, Volker;Hernquist, Lars
宇宙再电离的一个基本要求是星系发射的电离光子中有足够的部分成功逃逸到星系际介质中。然而，由于高红移观测数据的缺乏，驱动再电离的来源仍然不确定。在这项工作中，我们通过最先进的模拟计算了再电离时代星系的电离逃逸分数 (fesc)，该模拟将精确的辐射流体动力学求解器 (arepo-rt) 与经过充分测试的 IllustrisTNG 星系形成模型相结合，以自洽地模拟整个宇宙的小尺度星系物理和大规模再电离 ()。这使得形成大量巨大的光晕（），这些光晕在以前的研究中通常在统计上代表性不足，但被认为对于实现快速再电离很重要。我们发现低质量星系 () 是 z≳ 7 以上再电离的主要驱动力，而高质量星系 () 在较低红移下主导逃逸电离光子预算。我们发现，有效恒星形成率（SFR）表面密度（定义为每个逃逸区域每气体质量的恒星形成率）有很强的依赖性，即，对于较高质量的晕，晕逃逸分数的变化会减少，这可以从更稳定的星系结构、SFR稳定性和每个晕内对逃逸通量有显着贡献的视线分数来理解。尘埃能够减少大质量星系的逃逸分数，但对全球星系的影响取决于尘埃模型。最后，活动星系核对于星系中的再电离并不重要，并且由于位于星系引力势阱中心附近，它们的逃逸分数低于恒星核。
A fundamental requirement for reionizing the Universe is that a sufficient fraction of the ionizing photons emitted by galaxies successfully escapes into the intergalactic medium. However, due to the scarcity of high-redshift observational data, the sources driving reionization remain uncertain. In this work, we calculate the ionizing escape fractions (fesc) of reionization-era galaxies from the state-of-the-artthesansimulations, which combine an accurate radiation-hydrodynamic solver (arepo-rt) with the well-tested IllustrisTNG galaxy formation model to self-consistently simulate both small-scale galaxy physics and large-scale reionization throughout a large patch of the universe (). This allows the formation of numerous massive haloes (), which are often statistically underrepresented in previous studies but are believed to be important to achieving rapid reionization. We find that low-mass galaxies () are the main drivers of reionization abovez≳ 7, while high-mass galaxies () dominate the escaped ionizing photon budget at lower redshifts. We find a strong dependence offescon the effective star formation rate (SFR) surface density defined as the SFR per gas mass per escape area, i.e.. The variation in halo escape fractions decreases for higher mass haloes, which can be understood from the more settled galactic structure, SFR stability, and fraction of sightlines within each halo significantly contributing to the escaped flux. Dust is capable of reducing the escape fractions of massive galaxies, but the impact on the globalfescdepends on the dust model. Finally, active galactic nuclei are unimportant for reionization inthesanand their escape fractions are lower than stellar ones due to being located near the centres of galaxy gravitational potential wells.