Mapping the low-surface brightness Universe in the UV band with Lyα emission from IGM filaments
Mapping the low-surface brightness Universe in the UV band with Lyα emission from IGM filaments
复制标题
利用 IGM 灯丝的 Lyα 发射绘制 UV 波段的低表面亮度宇宙图
DOI：
10.1093/mnras/stw1777
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发表时间：
2016
影响因子：
4.8
通讯作者：
S. Zaroubi
中科院分区：
文献类型：
--
作者：
Marta B. Silva;R. Kooistra;S. Zaroubi
宇宙中很大一部分重子物质位于星系间介质（IGM）的细丝中。然而，除了环银河系介质中非常特殊的区域外，这些细丝的低表面亮度还不允许直接检测到它们。在这里，我们模拟了 IGM 灯丝的莱曼 α (Lyα) 发射的强度和空间波动，并讨论了下一代天基仪器在紫外 (UV) 波长下探测低表面亮度宇宙的前景。从高分辨率 N 体模拟开始，我们获得了暗物质密度波动，并将重子与暗物质粒子关联起来，假设它们遵循相同的空间分布。 IGM 热和电离状态由 UV 背景模型以及氢气和氦气的相关冷却过程设定。然后，考虑复合和碰撞激发过程，估计 Lyα 发射率。我们发现，通过 Lyα 发射来检测这些灯丝完全可以通过下一代紫外空间仪器来实现，因此应该在未来十年内实现。密度场充满了光晕和星系，并估计了它们的 Lyα 发射。星系被视为前景，因此我们讨论减少观测图污染的方法。最后，我们将 UV 连续谱背景估计为 Lyα 发射线红移的函数，并讨论该连续谱如何影响观测。
A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium (IGM). However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in the circum-galactic medium. Here we simulate the intensity and spatial fluctuations in Lyman alpha (Lyα) emission from filaments in the IGM and discuss the prospects for the next generation of space-based instruments to detect the low-surface brightness Universe at ultraviolet (UV) wavelengths. Starting with a high-resolution N-body simulation, we obtain the dark matter density fluctuations and associate baryons with the dark matter particles assuming that they follow the same spatial distribution. The IGM thermal and ionization state is set by a model of the UV background and by the relevant cooling processes for a hydrogen and helium gas. The Lyα emissivity is then estimated, taking into account recombination and collisional excitation processes. We find that the detection of these filaments through their Lyα emission is well in the reach of the next generation of UV space-based instruments and so it should be achieved in the next decade. The density field is populated with halos and galaxies and their Lyα emission is estimated. Galaxies are treated as foregrounds and so we discuss methods to reduce their contamination from observational maps. Finally, we estimate the UV continuum background as a function of the redshift of the Lyα emission line and discuss how this continuum can affect observations.