标题： 理解COSMOS星系二维相关函数在z~1时的形状 显示英文标题

标题： Understanding the shape of the galaxy two-point correlation function at z~1 in the COSMOS field

摘要： 我们研究了在zCOSMOS巡天中测量的星系两点相关函数的形状如何依赖于局域环境，这种局域环境以5 Mpc/h尺度上的密度对比来量化。 我们表明，在红移z=0.6到z=1之间观察到的平坦形状可以通过这一体积相对于宇宙密度概率分布函数简单地在高密度环境中多出10%来解释。 当排除分布顶部的10%样本时，测得的w_p(r_p)变陡，并且在所有尺度上变得与LCDM预测无法区分。 这与Abbas和Sheth在z~0的SDSS数据中识别出的效果相同，并被解释为等级场景中晕-环境相关性的自然结果。 生活在高密度区域中的星系追踪通常具有更高质量的暗物质晕，这些晕之间更加相关。 如果由于样本有限大小引入的变化导致样本的密度概率分布函数在高密度区域特别丰富，则会产生扭曲的两点相关函数。 我们认为这是导致COSMOS场中观测到的“奇特”聚类现象的主要效应。 显示英文摘要

摘要： We investigate how the shape of the galaxy two-point correlation function as measured in the zCOSMOS survey depends on local environment, quantified in terms of the density contrast on scales of 5 Mpc/h. We show that the flat shape previously observed at redshifts between z=0.6 and z=1 can be explained by this volume being simply 10% over-abundant in high-density environments, with respect to a Universal density probability distribution function. When galaxies corresponding to the top 10% tail of the distribution are excluded, the measured w_p(r_p) steepens and becomes indistinguishable from LCDM predictions on all scales. This is the same effect recognised by Abbas & Sheth in the SDSS data at z~0 and explained as a natural consequence of halo-environment correlations in a hierarchical scenario. Galaxies living in high-density regions trace dark matter halos with typically higher masses, which are more correlated. If the density probability distribution function of the sample is particularly rich in high-density regions because of the variance introduced by its finite size, this produces a distorted two-point correlation function. We argue that this is the dominant effect responsible for the observed "peculiar" clustering in the COSMOS field.