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arXiv 1409.8286astro-ph.COgr-qc
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用SKA星系红移巡天探测原始非高斯性:完全相对论分析

Probing primordial non-Gaussianity with SKA galaxy redshift surveys: a fully relativistic analysis

Stefano Camera, Mario G. Santos, Roy Maartens

摘要:

平方公里阵列(SKA)将对数千万到数亿个HI星系进行光谱调查,最终覆盖30,000平方公里。°的并延伸到红移z~2。SKA探测的巨大体积将允许对原始非高斯性的一些最佳约束,基于对大尺度功率谱的测量。我们调查各种观测设置HI星系红移调查,兼容SKA第1阶段和第2阶段(全SKA)配置。我们使用相应的数量计数和偏差为每个调查从现实的模拟和衍生的放大偏差和源计数的演变直接从这些。这是第一次,我们产生的预测,充分包括广义相对论对星系数计数的影响。这些对标准分析的修正在非常大的尺度上变得重要,在那里原始非高斯性的信号变得最强。我们的研究结果表明,对于完整的调查,非高斯参数fNL可以被约束到1.54的精度。这将普朗克卫星设定的电流限制提高了五倍,使用了完全不同的方法。

英文摘要:

The Square Kilometre Array (SKA) will produce spectroscopic surveys of tens to hundreds of millions of HI galaxies, eventually covering 30,000 sq. deg. and reaching out to redshift z~2. The huge volumes probed by the SKA will allow for some of the best constraints on primordial non-Gaussianity, based on measurements of the large-scale power spectrum. We investigate various observational set-ups for HI galaxy redshift surveys, compatible with the SKA Phase 1 and Phase 2 (full SKA) configurations. We use the corresponding number counts and bias for each survey from realistic simulations and derive the magnification bias and the evolution of source counts directly from these. For the first time, we produce forecasts that fully include the general relativistic effects on the galaxy number counts. These corrections to the standard analysis become important on very large scales, where the signal of primordial non-Gaussianity grows strongest. Our results show that, for the full survey, the non-Gaussianity parameter fNL can be constrained down to an accuracy of 1.54. This improves the current limit set by the Planck satellite by a factor of five, using a completely different approach.

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