Optimizing Spectroscopic and Photometric Galaxy Surveys: Same-Sky Benefits for Dark Energy and Modified Gravity
Optimizing Spectroscopic and Photometric Galaxy Surveys: Same-Sky Benefits for Dark Energy and Modified Gravity
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DOI：
10.1093/mnras/stv1268
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发表时间：
2013-07
影响因子：
4.8
通讯作者：
D. Kirk;O. Lahav;S. Bridle;S. Jouvel;F. Abdalla;J. Frieman
中科院分区：
文献类型：
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作者：
D. Kirk;O. Lahav;S. Bridle;S. Jouvel;F. Abdalla;J. Frieman
多个宇宙学探测器的组合可以产生比任何单个探测器更严格的宇宙学参数测量。我们研究了两个高度相关的晚期结构生长探针的组合：（i）来自光度红移调查的弱引力透镜效应和（ii）来自光谱红移调查的星系聚类和红移空间扭曲。我们选择通用调查设计，以便我们的结果适用于一系列当前和未来的光度红移（例如 KiDS、DES、HSC、Euclid）和光谱红移（例如 DESI、4MOST、Sumire）调查。结合这些调查极大地提高了他们测量暗能量和修正重力的能力。独立、不重叠的组合所得到的暗能量品质因数比单独任何一项调查所产生的暗能量品质因数大 4 倍以上。这些调查之间的强大协同作用对于修正重力来说是最强的，它们的约束是正交的，产生的非重叠联合品质因数比单独的任何一个都要大近2个数量级。当观测在天空上重叠时，我们的投影角功率谱形式可以轻松地对可观察到的互相关进行建模，从而产生联合数据向量和完整协方差矩阵。我们通过包含这些互相关性，计算相对于非重叠调查的同一天空改进因子。我们发现暗能量接近 4 倍，修正引力则超过 2 倍。准确的预测品质值和同天空效益可能会受到一系列预测假设的根本影响，我们在敏感性分析中系统地探讨了这些假设。我们表明，我们的基准假设产生了稳健的结果，可以很好地平均了解光度测量和光谱测量相结合的科学回报。
The combination of multiple cosmological probes can produce measurements of cosmological parameters much more stringent than those possible with any individual probe. We examine the combination of two highly correlated probes of late-time structure growth: (i) weak gravitational lensing from a survey with photometric redshifts and (ii) galaxy clustering and redshift space distortions from a survey with spectroscopic redshifts. We choose generic survey designs so that our results are applicable to a range of current and future photometric redshift (e.g. KiDS, DES, HSC, Euclid) and spectroscopic redshift (e.g. DESI, 4MOST, Sumire) surveys. Combining the surveys greatly improves their power to measure both dark energy and modified gravity. An independent, non-overlapping combination sees a dark energy figure of merit more than 4 times larger than that produced by either survey alone. The powerful synergies between the surveys are strongest for modified gravity, where their constraints are orthogonal, producing a non-overlapping joint figure of merit nearly 2 orders of magnitude larger than either alone. Our projected angular power spectrum formalism makes it easy to model the cross-correlation observable when the surveys overlap on the sky, producing a joint data vector and full covariance matrix. We calculate a same-sky improvement factor, from the inclusion of these cross-correlations, relative to non-overlapping surveys. We find nearly a factor of 4 for dark energy and more than a factor of 2 for modified gravity. The exact forecast figures of merit and same-sky benefits can be radically affected by a range of forecasts assumption, which we explore methodically in a sensitivity analysis. We show that that our fiducial assumptions produce robust results which give a good average picture of the science return from combining photometric and spectroscopic surveys.