The X-ray cluster survey with eRosita: forecasts for cosmology, cluster physics and primordial non-Gaussianity
The X-ray cluster survey with eRosita: forecasts for cosmology, cluster physics and primordial non-Gaussianity
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DOI：
10.1111/j.1365-2966.2012.20443.x
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发表时间：
2011-11
影响因子：
4.8
通讯作者：
A. Pillepich;C. Porciani;T. Reiprich
中科院分区：
文献类型：
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作者：
A. Pillepich;C. Porciani;T. Reiprich
从2013年底开始，该望远镜将以前所未有的灵敏度观测X射线天空。假设在(0.5-2.0)keV能带内的探测极限为50个光子，典型的曝光时间为1.6k，按照目前计划的全天探测，我们预计将探测到质量大于5×1013h∼1M⊙的9.3×10~4个星系团。他们的红移中值将是z≃0.35.我们使用费雪矩阵分析来预测Λ冷暗物质(Λ)宇宙学的约束力，同时预测星系团的X射线标度关系。特别关注发现原始的非高斯主义的可能性。我们考虑了两个实验探测器：光子计数有限的团簇样本的数目计数和角度聚集。我们讨论了如何分割星团样本以优化分析，并证明了单个星团的红移信息对于打破模型参数之间的强简并是至关重要的。例如，基于光度-红移估计并结合一点和两点统计数据进行‘断层’分析，将在没有先验的情况下给出Δσ8≃0.036和ΔΩm≃0.012的边际1≃误差，并将当前关于光度-质量关系斜率的估计提高3倍。对于原始的非高斯性，单是星系团将分别给出局部模型、正交模型和等边模型的≃9、36和144。用光谱精度测量红移将进一步收紧近40%的限制(FNL除外，它显示出较小的改进)。最后，结合数据和普朗克卫星对宇宙微波背景中温度各向异性的分析，应该会给出对宇宙学和星系团内介质性质的敏感约束。
Starting in late 2013, the telescope will survey the X-ray sky with unprecedented sensitivity. Assuming a detection limit of 50 photons in the (0.5–2.0) keV energy band with a typical exposure time of 1.6 ks, we predict that will detect ∼9.3 × 104 clusters of galaxies more massive than 5 × 1013 h−1 M⊙, with the currently planned all-sky survey. Their median redshift will be z≃ 0.35. We perform a Fisher-matrix analysis to forecast the constraining power of on the Λ cold dark matter (ΛCDM) cosmology and, simultaneously, on the X-ray scaling relations for galaxy clusters. Special attention is devoted to the possibility of detecting primordial non-Gaussianity. We consider two experimental probes: the number counts and the angular clustering of a photon-count limited sample of clusters. We discuss how the cluster sample should be split to optimize the analysis and we show that redshift information of the individual clusters is vital to break the strong degeneracies among the model parameters. For example, performing a ‘tomographic’ analysis based on photometric-redshift estimates and combining one- and two-point statistics will give marginal 1σ errors of Δσ8≃ 0.036 and ΔΩm≃ 0.012 without priors, and improve the current estimates on the slope of the luminosity–mass relation by a factor of 3. Regarding primordial non-Gaussianity, clusters alone will give ΔfNL≃ 9, 36 and 144 for the local, orthogonal and equilateral model, respectively. Measuring redshifts with spectroscopic accuracy would further tighten the constraints by nearly 40 per cent (barring fNL which displays smaller improvements). Finally, combining data with the analysis of temperature anisotropies in the cosmic microwave background by the Planck satellite should give sensational constraints on both the cosmology and the properties of the intracluster medium.