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未来超新星和计数巡天的红移精度要求

Redshift Accuracy Requirements for Future Supernova and Number Count Surveys

Dragan Huterer, Alex Kim, Lawrence M. Krauss, Tamara Broderick

摘要:

我们调查所需的红移精度的Ia型超新星和集群数计数调查,以便红移的不确定性不明显的贡献的暗能量参数误差预算。对于SNAP超新星实验,我们发现,如果没有地面测量的帮助,单个超新星的红移需要确定为约0.002或更好,这对于低分辨率光谱仪来说是一个具有挑战性但可行的要求。然而,我们发现,精确的红移z<0.1超新星,获得地面实验,足以免疫的结果,即使相对较大的红移误差在高z。对于未来的星系团数计数调查,如南极望远镜,普朗克或DUET,我们发现,在测光红移的纯统计误差是不太重要的,和不可约的,系统的偏见,在红移驱动的要求。红移偏差必须保持在0.001-0.005/红移区间(由滤波器组决定)以下,这取决于天空覆盖范围和巡天最小质量定义的细节。此外,我们发现X射线巡天比Sunyaev-Zeldovich(SZ)效应巡天对红移精度的要求更严格,因为它们在红移中使用了更短的杠杆臂;相反,SZ巡天只有在遥远(z>1)星系团的一些红移信息可用时才能受益于它们的高红移范围。

英文摘要:

We investigate the required redshift accuracy of type Ia supernova and cluster number-count surveys in order for the redshift uncertainties not to contribute appreciably to the dark energy parameter error budget. For the SNAP supernova experiment, we find that, without the assistance of ground-based measurements, individual supernova redshifts would need to be determined to about 0.002 or better, which is a challenging but feasible requirement for a low-resolution spectrograph. However, we find that accurate redshifts for z<0.1 supernovae, obtained with ground-based experiments, are sufficient to immunize the results against even relatively large redshift errors at high z. For the future cluster number-count surveys such as the South Pole Telescope, Planck or DUET, we find that the purely statistical error in photometric redshift is less important, and that the irreducible, systematic bias in redshift drives the requirements. The redshift bias will have to be kept below 0.001-0.005 per redshift bin (which is determined by the filter set), depending on the sky coverage and details of the definition of the minimal mass of the survey. Furthermore, we find that X-ray surveys have a more stringent required redshift accuracy than Sunyaev-Zeldovich (SZ) effect surveys since they use a shorter lever arm in redshift; conversely, SZ surveys benefit from their high redshift reach only so long as some redshift information is available for distant (z>1) clusters.

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