We describe a method for constructing mock galaxy catalogues which are well suited for use in conjunction with large photometric surveys. We use the semi-analytic galaxy formation model of Bower et al. implemented in the Millennium simulation. We apply our method to the specific case of the surveys soon to commence with PS1, the first of 4 telescopes planned for the Pan-STARRS system. PS1 has 5 photometric bands (grizy), and will carry out an all-sky 3pi survey and a medium deep survey (MDS) over 84 sq.deg. We calculate the expected magnitude limits for extended sources in the two surveys. We find that, after 3 years, the 3pi survey will have detected over 10^8 galaxies in all 5 bands, 10 million of which will lie at redshift z>0.9, while the MDS will have detected over 10^7 galaxies with 0.5 million lying at z>2. These numbers at least double if detection in the shallowest band, y is not required. We then evaluate the accuracy of photometric redshifts estimated using an off-the-shelf photo-z code. With the grizy bands alone it is possible to achieve an accuracy in the 3pi survey of Delta z/(1+z)~0.06 for 0.25<z<0.8, which could be reduced by about 15% using near infrared photometry from the UKIDDS survey, but would increase by about 25% for the deeper sample without the y band photometry. For the MDS an accuracy of Delta z/(1+z)~0.05 is achievable for 0.02<z<1.5 using grizy. A dramatic improvement in accuracy is possible by selecting only red galaxies. In this case, Delta z/(1+z)~0.02-0.04 is achievable for ~100 million galaxies at 0.4<z<1.1 in the 3pi survey and for 30 million galaxies in the MDS at 0.4<z<2. We investigate the effect of using photo-z in the estimate of the baryonic acoustic oscillation scale. We find that PS1 will achieve a similar accuracy in this estimate as a spectroscopic survey of 20 million galaxies.
Luminosity dependence of the spatial and velocity distributions of galaxies: Semi-analytic models versus the Sloan Digital Sky Survey
通过比较半解析星系星表与斯隆数字巡天（SDSS）的数据，我们表明，目前的星系形成模型再现定性的依赖星系集群和成对的特有速度对光度，但一些微妙的差异与数据仍然存在。通过构建一个大型的模拟星系红移调查，具有相同的选择功能的SDSS数据发布四（DR 4）的比较。模拟巡天是基于Croton等人和Kang等人提出的两套半解析星表，从模拟星表中，我们测量了不同光度区间星系的红移空间投影两点关联函数、功率谱和傅立叶空间和位形空间的成对速度色散（PVD）。然后，我们将这些理论预测与来自SDSS DR 4的测量结果进行比较。在大尺度上，对于比L* 亮的星系，两组模拟星表都与数据吻合得很好。然而，对于较暗的星系，这两个模型预测更强的集群和更高的成对速度比观察。我们证明，这个问题可以得到解决，如果在大规模的晕的微弱卫星星系的分数减少了~30%的模型预测相比。直接观察模型星系目录显示，有相当一部分（15%）的暗星系（$-18<M_{^{0.1}r}<-17$）居住在具有$M_{vir}>10^{13}\msun$的晕中，并且这些星系主要是红色的。这些微弱的红色星系是低光度星系在小尺度上的高PVD值的原因。
GalICS V : Low and high order clustering in mock SDSS's
[摘要]我们使用基于GALICS模型（Hatton et al. 03）的模拟星表来探索SDSS中观察到的星系团的性质。我们测量低，高阶角聚类统计从这些模拟目录，选择星系后，以同样的方式为观察，并将它们直接从SDSS数据的估计。请注意，我们还提供了SDSS DR 1上S3-S5的测量结果。我们发现，我们的模型是在一般的尺度/光度范围内，我们可以信任的预测与观察良好的协议。这个范围被发现是有限的（i）的大小所使用的暗物质模拟-这在大尺度上引入了有限体积效应-和质量分辨率的模拟-这引入了不完整的表观大小比$r\sim 20$。然后，我们专注于小规模的星系集群的属性和调查的行为，三个不同的处方内的暗物质晕定位星系。我们发现，星系是穷人示踪剂的DM粒子或DM子结构，集团和集群。相反，SDSS数据告诉我们，星系的分布在这两个群体之间。这证实了数值模拟和半解析建模的一般理论预期。
