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arXiv 1509.03312astro-ph.COastro-ph.GA
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用SKA探测再电离天体物理的最佳堆芯基线设计和观测策略

Optimal core baseline design and observing strategy for probing the astrophysics of reionization with the SKA

Bradley Greig, Andrei Mesinger, Léon V. E. Koopmans

摘要:

随着平方公里阵列(SKA 1)的第一阶段进入最后的预建设阶段,我们研究如何最大限度地提高其科学回报。具体来说,我们专注于统计测量的21厘米功率谱(PS)的再电离时代(EoR)使用低频阵列,SKA 1-低。为了方便这项调查,我们使用最近开发的MCMC为基础的EoR分析工具21 CMMC(格雷格和梅辛格)。鉴于最近成本降低了50%,我们考虑了几种不同的SKA核心基线设计,改变了:(一)天线站的数量;(二)每个站的偶极子数量;以及(三)基线长度的分布。我们发现,一个设计与减少每个核心站的偶极子数量(增加的视野和核心站的总数),连同缩短基线,最大限度地恢复EoR信号。有了这个最佳的基线设计,我们调查三个观察策略,分析降低仪器的热噪声对增加视野之间的权衡。SKA 1-low计划执行三层观测方法,包括1000 h时的深100 deg $^{2}$、100 h时的中深1000 deg $^{2}$和10 h时的浅10,000 deg $^{2}$。我们发现,这三种观测策略的结果在可比的($\lesssim$ %)约束我们的EOR天体物理参数。这与纯粹基于总信噪比的天真预测相反,因此突出了使用EoR参数约束作为品质因数的必要性,以便最大限度地提高下一代干涉仪的科学回报。

英文摘要:

With the first phase of the Square Kilometre Array (SKA1) entering into its final pre-construction phase, we investigate how best to maximise its scientific return. Specifically, we focus on the statistical measurement of the 21 cm power spectrum (PS) from the epoch of reionization (EoR) using the low frequency array, SKA1-low. To facilitate this investigation we use the recently developed MCMC based EoR analysis tool 21CMMC (Greig & Mesinger). In light of the recent 50 per cent cost reduction, we consider several different SKA core baseline designs, changing: (i) the number of antenna stations; (ii) the number of dipoles per station; and also (iii) the distribution of baseline lengths. We find that a design with a reduced number of dipoles per core station (increased field of view and total number of core stations), together with shortened baselines, maximises the recovered EoR signal. With this optimal baseline design, we investigate three observing strategies, analysing the trade-off between lowering the instrumental thermal noise against increasing the field of view. SKA1-low intends to perform a three tiered observing approach, including a deep 100 deg$^{2}$ at 1000 h, a medium-deep 1000 deg$^{2}$ at 100 h and a shallow 10,000 deg$^{2}$ at 10 h survey. We find that the three observing strategies result in comparable ($\lesssim$ per cent) constraints on our EoR astrophysical parameters. This is contrary to naive predictions based purely on the total signal-to-noise, thus highlighting the need to use EoR parameter constraints as a figure of merit, in order to maximise scientific returns with next generation interferometers.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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