标题： 用MICE模拟宇宙：大质量星团的丰度 显示英文标题

标题： Simulating the Universe with MICE: The abundance of massive clusters

摘要： 我们引入了一组新的大规模N体模拟，即MICE模拟，它提供了非常大的宇宙体积与良好的质量分辨率的独特组合。它们追踪了约85亿个粒子（2048³）在覆盖高达450(Gpc/h)³的体积中的引力演化。我们的主要目标是准确建模和校准即将进行的天文巡天所使用的最基本的宇宙探测方法。在这里，我们利用MICE的巨大体积来对晕星系质量函数（MF）的高质量尾部进行稳健采样。我们讨论并避免了研究中可能出现的系统性效应，并对不同的误差估计器进行了详细分析。我们发现，Warren等人（2006年）对局部晕星系丰度的现有拟合在M~10^{14}\Msun 范围内很好地匹配了MICE中的丰度，但对于更大质量的晕星系显著偏离，在M=3.16×10^{14}\Msun （10^{15}\Msun ）时低估了质量函数分别约为10%（30%）。 同样地，广泛使用的 Sheth & Tormen（1999）拟合公式，如果假设普遍性并外推到高红移，则会导致在 z=0、0.5 和 1 时星团丰度分别低估 30%、20% 和 15%，对于 M ~ [7 - 2.5 - 0.8] × 10^{14}\Msun （$\nu = \delta_c/\sigma ~ 3$）的情况。 我们提供了一个重新校准的 halo 质量函数（MF），其有效范围跨越了 5 个数量级的质量，即 10^{10} < M/(\Msun ) < 10^{15}，并且能够精确描述其随红移的演化，直到 z=1。 我们探讨了这一重新校准对暗能量测定的影响，并得出结论：使用现有的拟合公式可能会使 w 的估计值产生高达 50% 的系统偏差，特别是在中等深度（z <= 1）的巡天调查中。 MICE halo 目录可以在 http://www.ice.cat/mice 公开获取。 显示英文摘要

摘要： We introduce a new set of large N-body runs, the MICE simulations, that provide a unique combination of very large cosmological volumes with good mass resolution. They follow the gravitational evolution of ~ 8.5 billion particles (2048^3) in volumes covering up to 450 (Gpc/h)^3. Our main goal is to accurately model and calibrate basic cosmological probes that will be used by upcoming astronomical surveys. Here we take advantage of the very large volumes of MICE to make a robust sampling of the high-mass tail of the halo mass function (MF). We discuss and avoid possible systematic effects in our study, and do a detailed analysis of different error estimators. We find that available fits to the local abundance of halos (Warren et al. (2006)) match well the abundance in MICE up to M ~ 10^{14}\Msun, but significantly deviate for larger masses, underestimating the mass function by 10% (30%) at M = 3.16 x 10^{14}\Msun (10^{15}\Msun). Similarly, the widely used Sheth & Tormen (1999) fit, if extrapolated to high redshift assuming universality, leads to an underestimation of the cluster abundance by 30%, 20% and 15% at z=0, 0.5, 1 for M ~ [7 - 2.5 - 0.8] x 10^{14}\Msun respectively ($\nu = \delta_c/\sigma ~ 3$). We provide a re-calibration of the halo MF valid over 5 orders of magnitude in mass, 10^{10} < M/(\Msun) < 10^{15}, that accurately describes its redshift evolution up to z=1. We explore the impact of this re-calibration on the determination of dark-energy, and conclude that using available fits may systematically bias the estimate of w by as much as 50% for medium-depth (z <= 1) surveys. MICE halo catalogues are publicly available at http://www.ice.cat/mice