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A Flexible Analytic Model of Cosmic Variance in the First Billion Years
Monthly Notices of the Royal Astronomical Society ( IF 4.7 ) Pub Date : 2020-09-22 , DOI: 10.1093/mnras/staa2828
A C Trapp 1 , Steven R Furlanetto 1
Affiliation  

Author(s): Trapp, AC; Furlanetto, Steven R | Abstract: ABSTRACT Cosmic variance is the intrinsic scatter in the number density of galaxies due to fluctuations in the large-scale dark matter density field. In this work, we present a simple analytic model of cosmic variance in the high-redshift Universe (z ∼ 5–15). We assume that galaxies grow according to the evolution of the halo mass function, which we allow to vary with large-scale environment. Our model produces a reasonable match to the observed ultraviolet (UV) luminosity functions in this era by regulating star formation through stellar feedback and assuming that the UV luminosity function is dominated by recent star formation. We find that cosmic variance in the UV luminosity function is dominated by the variance in the underlying dark matter halo population, and not by differences in halo accretion or the specifics of our stellar feedback model. We also find that cosmic variance dominates over Poisson noise for future high-z surveys except for the brightest sources or at very high redshifts (z ≳ 12). We provide a linear approximation of cosmic variance for a variety of redshifts, magnitudes, and survey areas through the public python package galcv. Finally, we introduce a new method for incorporating priors on cosmic variance into estimates of the galaxy luminosity function and demonstrate that it significantly improves constraints on that important observable.

中文翻译:

前十亿年宇宙变化的灵活分析模型

作者(S):特拉普,AC;Furlanetto,史蒂文R | 摘要: 摘要 宇宙方差是由于大尺度暗物质密度场的波动引起的星系数密度的内在散射。在这项工作中,我们提出了高红移宇宙(z ∼ 5-15)中宇宙方差的简单分析模型。我们假设星系根据晕质量函数的演化而增长,我们允许它随大尺度环境而变化。我们的模型通过恒星反馈调节恒星形成,并假设紫外线光度函数由最近的恒星形成主导,从而与该时代观测到的紫外线 (UV) 光度函数产生合理匹配。我们发现紫外光度函数的宇宙方差主要由潜在暗物质晕群的方差决定,而不是光环吸积的差异或我们恒星反馈模型的细节。我们还发现,除了最亮的源或非常高的红移 (z ≳ 12) 外,宇宙方差在未来高 z 测量中占主导地位。我们通过公共 python 包 galcv 为各种红移、星等和调查区域提供了宇宙方差的线性近似值。最后,我们引入了一种新方法,用于将宇宙方差的先验纳入星系光度函数的估计中,并证明它显着改善了对该重要可观测值的约束。我们通过公共 python 包 galcv 为各种红移、星等和调查区域提供了宇宙方差的线性近似值。最后,我们引入了一种新方法,用于将宇宙方差的先验纳入星系光度函数的估计中,并证明它显着改善了对该重要可观测值的约束。我们通过公共 python 包 galcv 为各种红移、星等和调查区域提供了宇宙方差的线性近似值。最后,我们引入了一种新方法,用于将宇宙方差的先验纳入星系光度函数的估计中,并证明它显着改善了对该重要可观测值的约束。
更新日期:2020-09-22
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