Cosmic Voids and Galaxy Bias in the Halo Occupation Framework
Cosmic Voids and Galaxy Bias in the Halo Occupation Framework
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光环占领框架中的宇宙空洞和星系偏差
DOI：
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发表时间：
2006
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通讯作者：
M. Warren
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作者：
J. Tinker;D. Weinberg;M. Warren
我们研究了空洞统计在限制星系偏差和暗物质波动幅度方面的能力。我们采用了Λ清洁发展机制的宇宙学情景(具有宇宙常数的膨胀冷暗物质)，并使用晕占据分布框架来描述星系和暗物质之间的关系。在选择了HOD参数来再现平均空间密度g和投影相关函数wp(Rp)之后，我们通过填充大型高分辨率N体模拟(400h-1 MPC，12803粒子)的晕来预测这些样本的空洞概率函数和欠密度概率函数。如果我们做一个常规的简化假设，即HOD在固定晕质量时与大尺度环境无关，那么约束匹配g和wp(Rp)的模型将预测几乎相同的空洞统计，而与晕质量和中心星系光度之间的散射或HOD参数中的统计不确定性无关。功率谱归一化σ8=0.7和0.9的模型也预测了非常相似的空洞统计数据，在低σ8模型中，较强的星系偏向补偿了较弱的暗物质波动。然而，VPF和UPF对HOD的环境变化很敏感，在这些变化对wp(Rp)影响很小的区域。例如，在大尺度(5h-1Mpc)密度对比度为δ<；-0.65的区域，将最小宿主晕质量加倍对MR<；-19星系的空洞概率有明显的影响，而δ<；-0.2区的类似变化在可检测的水平上改变了MR<；-21星系的空洞概率。VPF和UPF提供了关于HOD中密度依赖的开始和程度的补充信息。通过探测或排除低密度区的HOD变化，空洞统计可以减少由HOD模型得出的宇宙学约束中的系统不确定性，更重要的是，揭示光晕形成历史和星系属性之间的联系。
We investigate the power of void statistics to constrain galaxy bias and the amplitude of dark matter fluctuations. We adopt a ΛCDM cosmological scenario (inflationary cold dark matter with a cosmological constant) and use the halo occupation distribution (HOD) framework to describe the relation between galaxies and dark matter. After choosing HOD parameters that reproduce the mean space density g and projected correlation function wp(rp) measured for galaxy samples with Mr < -19 and -21 from the Sloan Digital Sky Survey (SDSS), we predict the void probability function (VPF) and underdensity probability function (UPF) of these samples by populating the halos of a large, high-resolution N-body simulation (400 h-1 Mpc, 12803 particles). If we make the conventional simplifying assumption that the HOD is independent of large-scale environment at fixed halo mass, then models constrained to match g and wp(rp) predict nearly identical void statistics, independent of the scatter between halo mass and central galaxy luminosity or statistical uncertainties in HOD parameters. Models with power spectrum normalizations σ8 = 0.7 and 0.9 also predict very similar void statistics, with stronger galaxy bias compensating for weaker dark matter fluctuations in the low-σ8 model. However, the VPF and UPF are sensitive to environmental variations of the HOD in a regime where these variations have little impact on wp(rp). For example, doubling the minimum host halo mass in regions with large-scale (5 h-1 Mpc) density contrast δ < -0.65 has a readily detectable impact on void probabilities of Mr < -19 galaxies, and a similar change for δ < -0.2 alters the void probabilities of Mr < -21 galaxies at a detectable level. The VPF and UPF provide complementary information about the onset and magnitude of density dependence in the HOD. By detecting or ruling out HOD changes in low-density regions, void statistics can reduce systematic uncertainties in the cosmological constraints derived from HOD modeling and, more importantly, reveal connections between halo formation history and galaxy properties.